Grade 9 / Proportionality 62 exercises (100% corrected)

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ChingQuizz : 1 exercise available for Quizz assessment : 1. Equality of fractions (equations) E.1856 1 Copy and complete the following equations correctly: a 3 × = 4 b 3 2 × = 4 5 c 1 2 × = 7 5 2 Using the cross product, find the different values of x making the following equalities true. Give the values in simplified forms : a 2 3 = x 5 b 7 x = 8 9 c 1 x = 3 E.1845 Test each of the equalities for the indicated value : a 5 7 = 3 x pour x = 21 5 b x 3 = 5 2 pour x = 15 2 c 3 2 = x 5 pour x = 15 2 d 2 x = 3 4 pour x = 8 3 E.1844 Using the cross product, determine the value of ˇ x ı verifying the equality: a 3 5 = 2 x b x 6 = 7 8 c 7 4 = 2 x d 2 x = 4 10 e 3 7 = x 4 f 5 4 = 1 x E.1052 Using the cross product, solve the following equations : a 2 3 = 5 x b x 3 = 7 2 c 2 3 = 3 x 2. Duration and speed E.11514 Note: The number 60 has 12 divisors, which allows for the following conversions : 12 min = 0 ; 2 h ; 15 min = 0 ; 25 h 30 min = 0 ; 5 h ; 45 min = 0 ; 75 h 1 At a normal, constant pace, a walker covers 1 km in 15 min . Give its speed in km = h . 2 A car traveling at a constant speed covers 56 km in 30 minutes. Give its speed in km = h . 3 An airliner flying at a constant speed covers 170 km in 12 minutes. Give its speed in km = h . E.11515 A man is walking and covers the 13.65 km of the city’s circumference in 3 h 15 min. Calculate the walking speed of this man in miles per hour. E.11516 Proposition: Average speed connects distance and dura-tion of uniform motion through three equivalent identities: v = d t d = v × t t = d v A commercial airliner flew from Paris to Mexico City in 11 h 50 min . We assume that its cruising speed of 238 m = s was maintained throughout the journey. Determine the distance traveled by this aircraft in km . E.11517 The marathon is a sporting event in which participants must run 42 195 m . The world record was set in 2003 at the Berlin Marathon in 2 h 05 min . Give its average speed expressed in km = h rounded to the near-est unit. E.11518 In 3 h 33 min , a driver traveled 291 ; 1 km . What was his aver-age speed in km = h ? E.11519 A runner covers 23 ; 4 km in 1 h 12 min . What was his average speed in km = h ? E.11520 A driver travels 212 ; 8 km in 1 h 54 min . What was his average speed in km = h ? E.11521 A driver travels 64 ; 4 km in 48 minutes. What was his speed in km = h ? E.11522 During a competition, a cyclist starts the race at 10 h 45 and finishes at 12 h 36 . The distance traveled is 51 ; 8 km . What was the average speed expressed in km = h ? E.11523 A cyclist travels 11 ; 4 km in 45 min . What was his average speed in km = h ? https://chingmath.fr chapExoCorrec/1856 sacados/1856 chapExoCorrec/1845 sacados/1845 chapExoCorrec/1844 sacados/1844 chapExoCorrec/1052 sacados/1052 chapExoCorrec/11514 sacados/11514 chapExoCorrec/11515 sacados/11515 chapExoCorrec/11516 sacados/11516 chapExoCorrec/11517 sacados/11517 chapExoCorrec/11518 sacados/11518 chapExoCorrec/11519 sacados/11519 chapExoCorrec/11520 sacados/11520 chapExoCorrec/11521 sacados/11521 chapExoCorrec/11522 sacados/11522 chapExoCorrec/11523 sacados/11523
E.11524 A driver drives at a constant speed of 111 km = h for 42 min . What distance did they travel? E.11525 A cyclist rides at a constant speed of 19 ; 5 km = h on a route of 35 ; 1 km . How long did the trip take? E.11526 A driver travels a distance of 141 ; 9 km . He leaves at 9 h 47 and arrives at 11 h 26 . Determine the average speed in km = h for this journey. E.11527 A cyclist sets off at 14 h 22 on a journey of 75 ; 4 km and rides at a speed of 39 km = h . What time will he finish his journey? 3. Reminders: proportionality and percentage E.874 Emilie and Antoine each make a chocolate cake. Antoine uses 100g chocolate, 20g flour and 30g milk pow-der. Emilie uses 220g chocolate, 45g flour and 58g powdered milk Calculate for the two cakes, the percentage of chocolate they contain respectively. Of Emilie and Antoine, who has the cake richer in chocolate? E.9236 According to the 2000 census, Mex-ico would have 102 million people, of whom 34 million would be under the age of 14 . What percentage does this age group represent of the total population? (value defaulted to the unit) E.898 1 What sums are 3.85 % of 150 000 e , 378 000 e , 500 000 e , then 1 000 000 e ? 2 What percentage, rounded to the nearest hundredth, of 500 000 e représente 14 553 e ? 3 What percentage, rounded to the nearest hundredth, of 1 000 000 e représente 14 553 e ? E.887 A miniature globe has a circumference of 40 cm , while the circumference of the earth is 40 000 km 1 Complete the following table : Circonférence Echelle Actual size (m) Reduced size (m) 2 Complete the dotted lines with the correct value : ˇ The scale of this thumbnail is 1 : : : : : : ı Definition: scale of a reduction is the coefficient of pro-portionality to go from ˇactual sizeı to ˇtaille réduiteı. E.893 The car below is a reduction of the Ferrari F40. In reality, its length is 4.44 meters. 1 a Give the scale of this representation b Knowing that the car (the real one) is 1.98 meters wide, give the width of this reduction to the nearest millime-ter. 2 Another reduction of this car is offered to scale 1 37 . Give the length of this new reduction. 4. Evolutions: introduction E.9228 In one year, the price of an object increased from 130 e to 149.5 e . We wish to determine the percentage increase experienced by the price of this object in 1 year. 1 By what amount did the price of this item increase? 2 Complete the table below : Référence Augmentation Prix Pourcentage 100 % 3 Complete the operations below to obtain the percentage increase experienced by the price of this object : From the cross product : x × : : : = : : : × : : : We derive : x = : : : × : : : : : : = : : : % https://chingmath.fr chapExoCorrec/11524 sacados/11524 chapExoCorrec/11525 sacados/11525 chapExoCorrec/11526 sacados/11526 chapExoCorrec/11527 sacados/11527 chapExoCorrec/874 sacados/874 chapExoCorrec/9236 sacados/9236 chapExoCorrec/898 sacados/898 chapExoCorrec/887 sacados/887 chapExoCorrec/893 sacados/893 chapExoCorrec/9228 sacados/9228
Valeur initialeAugmentationValeur ∏nale30050251215020%% Valeur initialeRéductionValeur ∏nale200501204405512%12% E.894 In one year, the number of students at a school has decreased from 1025 students to 943 students. We wish to determine the percentage reduction in enrollment for this facility: 1 By how many students has the school’s enrollment de-creased? 2 Complete the table below : Référence Réduction Effectif Pourcentage 100 % 3 Complete the operations below to obtain the percentage reduction experienced by the facility’s workforce: From the cross product : x × : : : = : : : × : : : We derive : x = : : : × : : : : : : = : : : % E.7919 1 In order to perform an augmentation of 20 % on a set of values, we use the table below to complete : 2 Justify that the rows ˇ Initial value ı and ˇ Final Value ı represent a proportionality situation for which the pro-portionality coefficient will be specified. E.7918 1 In order to perform a reduction of 12 % on a set of values, we use the table below to complete : 2 Justify that the rows ˇ Initial value ı and ˇ Final Value ı represent a proportionality situation for which the pro-portionality coefficient will be specified. 5. Evolution and proportionality coefficient E.872 Proposal: When a quantity increases by a % , the multiplier coef-ficient that reflects this change has a value of 1+ a 100 . When a quantity decreases by a % , the multiplier coef-ficient that reflects this change has a value of 1 a 100 . Match each of the following changes with the appropriate mul-tiplier coefficient : a 10 % b 12 % c 2 % d 112 % e 10 % f 25 % E.9232 Proposal: Consider a change with a multiplier coefficient of k : If k> 1 , then this change is an increase with a percent-age increase of a , which has a value of : a = k 1 × 100 If k< 1 , then this change is a decrease, the percentage a of which is : a = 1 k × 100 Associate each of the following multiplier coefficients with the nature of the corresponding change and its associated percent-age: a 1 ; 05 b 0 ; 8 c 1 ; 2 d 0 ; 95 e 1 ; 4 f 0 ; 6 E.10918 1 Associate the appropriate multiplying factor with each of the following changes : a 20 % b 3 % c 7.5 % 2 Associate with each of the following multiplier coeffi-cients, the nature of the corresponding evolution and its associated percentage: a 1.3 b 0.9 c 1.88 https://chingmath.fr chapExoCorrec/894 sacados/894 chapExoCorrec/7919 sacados/7919 Valeur initialeAugmentationValeur ∏nale30050251215020%% chapExoCorrec/7918 sacados/7918 Valeur initialeRéductionValeur ∏nale200501204405512%12% chapExoCorrec/872 sacados/872 chapExoCorrec/9232 sacados/9232 chapExoCorrec/10918 sacados/10918
E.10946 1 Associate the appropriate multiplying factor with each of the following changes : a 13 % b 18 % c 1.2 % 2 Associate with each of the following multiplier coeffi-cients, the nature of the corresponding evolution and its associated percentage: a 1.1 b 0.73 c 1.31 E.1126 1 To make an increase of 12 % , multiply by . . . . . . . . . the old price. 2 To make an increase of . . . . . . . . . %, multiply by 1.45 the old price. 3 To make a decrease of 12 % , multiply by . . . . . . . . . the old price. 4 To make a decrease of . . . . . . . . . %, multiply by 0.23 the old price. E.5573 1 What is the multiplier associated with an increase of 5 % ? 2 What is the multiplier associated with a reduction of 5 % ? 6. Evolution: search for future value E.9233 A merchant increases in January 2002 the prices of all its items from 12% . 1 Give the multiplier coefficient associated with this change. 2 A DVD player costs, before increase, 372 euros. How much will it cost afterwards? E.9234 A merchant increases the prices of all his items by 8 % . 1 Give the multiplier coefficient associated with this evo-lutino. 2 A DVD player costs, before increase, 329 euros. How much will it coùt after? E.885 The selling price, excluding tax, of a surfboard is 23 000 F . One must pay a TV A (value added tax) of 18 % . Calculate the selling price, to the public, of this surfboard. E.899 1 Give the multiplier coefficient associated with a reduc-tion of 7.5 % . 2 An object costs 132 e and undergoes a reduction of 7.5 % . What is its new price after the discount is applied? E.892 A store specializing in the sale of automobile accessories sells a model of tire at 120 e unit. During a promotion, he decides to offer a discount of 25 % on the purchase of each tire. Its advertising poster states : ˇLe 4 e tire is gratuitı. Is this correct? Justify. 7. Evolution: search for the initial value E.884 In January 2002 , a retailer increases the prices of all its items at 12% . 1 Give the multiplier coefficient associated with this evolu-tion. 2 A television set costs, after increase, 476 euros. How much did it cost before? E.891 A retailer increases the prices of all its products at 8 % . 1 Give the multiplier coefficient associated with this evolu-tion. 2 A television set costs, after increase, 540 euros. How much did it cost before? E.9238 An object, after undergoing a reduc-tion of 12 % , costs 48.4 e . What was the price of this object before the reduction? E.900 A shopkeeper increases the prices of all his items by 8% . 1 A DVD player costs, before increase, 329 euros. How much will it cost afterwards? 2 A television costs, after increase, 540 euros. How much did it cost before? E.1424 An appliance store is offering a dis-count of 12 % on all its items. 1 A television set cost 245 e . What will its new price be? 2 The price of a dryer after this discount is 435.6 e . Deter-mine the initial price of this dryer E.1457 In one store, the owner raises all his prices by 12 % . 1 A video recorder cost 215 e before increase. Give the price of this object after undergoing the increase. 2 And a DVD player has undergone an increase of 36 e . De-termine the price of this DVD player before the increase and its price after the increase. https://chingmath.fr chapExoCorrec/10946 sacados/10946 chapExoCorrec/1126 sacados/1126 chapExoCorrec/5573 sacados/5573 chapExoCorrec/9233 sacados/9233 chapExoCorrec/9234 sacados/9234 Groupe Ouest - Juin 2003 chapExoCorrec/885 sacados/885 chapExoCorrec/899 sacados/899 chapExoCorrec/892 sacados/892 chapExoCorrec/884 sacados/884 chapExoCorrec/891 sacados/891 Groupe Ouest - Juin 2003 chapExoCorrec/9238 sacados/9238 chapExoCorrec/900 sacados/900 Groupe Ouest - Juin 2003 - 2 points chapExoCorrec/1424 sacados/1424 chapExoCorrec/1457 sacados/1457
E.1421 1 a Aline goes shopping in a store running promotions. She buys an item originally worth 36 e and discounted by 25 % . Calculate its new price. b Another item cost 20.4 e after a discount of 15 % . De- termine the initial price of this object. 2 Give the purchase price of these two items before their reduction, then after their reduction. Deduct the total percentage discount on his two pur-chases. 8. Developments: rate search E.2116 Answer the following questions. No justification is required : 1 The price of an object has been multiplied by 1.56 . What is the associated percentage increase? 2 The number of pupils in a school has fallen. This num-ber has been multiplied by 0.86 . What is the associated percentage reduction? E.886 In a store, a video recorder costs 34 000 F and is sold at a price of 25 500 F . What is the percentage reduction from the original price? E.9230 During the sale period, the listed price of a dress is 4 500 F . After discount, the sale price of this dress is 3 825 F . What is the percentage of this discount? E.9235 Answer the following questions. No justification is required : 1 An object increased from 112 e à 156.8 e . What was the percentage increase? 2 A sale item costing 4 000 FCFA shows a discount of 1 500 FCA . What is the percentage discount given? E.9237 Arrived the month of July, the sales begin in France. A store displays 15 % on all items in its store. A sweater went from : 40 e à 34.4 e . Explain why the owner has been falsely advertising. 9. Evolution: initial value, future value and evolution rate E.1127 In its 1995 census, Mexico had 91.15 million inhabitants. Whereas in 2000 , there were 97.48 mil-lion inhabitants. 1 What is the percentage increase in population between these two dates? Round to the nearest tenth. 2 Whereas between 1980 and 2000 , the population grew by 43.1% . Give the population of Mexico in 1980 ? Round the result to the nearest ten thousand inhabitants. E.3377 Heimriri and her brother Tehui want to spoil their mom for Mother’s Day. They have 18 000 F and take advantage of the sales. 1 In the window of a jewelry store, they see beautiful 12 000 F earrings. Calculate the price of the earrings after a discount of 25 % ? 2 In the same jewelry store, they see a beautiful ring. After a discount of 20 % , the price of the ring is 7 840 F . What was its original price? 3 As Heimriri prepares to leave the jewelry store, she is charmed by a mother-of-pearl pendant. Here’s what the tag says : Pendant 2 800 F 2 100 F Determine the percentage discount taken on the price of this pendant. 10. Successive evolutions E.9229 A toy costs 100 e . It is first reduced by 10 % , then by a second reduction of 10 % : 1 What is the selling price of this toy after these two dis-counts? 2 What is the total ˇ percentage ı of the discount allocated to this toy? https://chingmath.fr chapExoCorrec/1421 sacados/1421 chapExoCorrec/2116 sacados/2116 chapExoCorrec/886 sacados/886 chapExoCorrec/9230 sacados/9230 chapExoCorrec/9235 sacados/9235 chapExoCorrec/9237 sacados/9237 chapExoCorrec/1127 sacados/1127 chapExoCorrec/3377 sacados/3377 chapExoCorrec/9229 sacados/9229
Réduction de10%Réduction de32%Augmentation de5%Augmentation de1%px↦−1;05×xpx↦−0;68×xpx↦−0;9×xpx↦−1;01×x E.7971 The manager of the largest multi-sport club in the region noted that between 2010 Jan-uary 1 er and 2012 December 31 , the total number of members increased by 10 % , and then increased again by 5 % between 2013 January 1 er and 2015 December 31 . The total number of members in 2010 was 1 000 . 1 Calculate and justify the total number of members on 31 December 2012 . 2 Calculate and justify the total number of members on December 31 2015 . 3 Martine thinks that on December 31 2015 , there should be 1 150 members, because she says : ˇ an increase of 10 % followed by another increase of 5 % , which makes a total increase of 15 % ı. What do you think? Explain your answer. E.9231 Note: All attempts, ideas, and approaches, even if unsuc-cessful or poorly formulated, will be taken into account for evaluation purposes. An item undergoes a successive increase of 5 % followed by a reduction of 5 % . Will the price of the item change? Please specify your answer. 11. Evolution and affine functions E.7924 Each evolution is associated with a linear function. For each of the proposed evolutions, associate the corresponding linear function : 12. Share E.4921 1 A dictionary costs 25 e . An increase of 16 % is applied to the price of this item. Give the new price of the dictionary. 2 A television has its price increased from 375 e à 270 e during a sale. Give the percentage discount applied to the price of this item. Justify your answer. E.10947 1 A television costs 191 e . A reduction of 11 % is applied to the price of this item. Give the new price of the television. 2 A cell phone has its price increased from 424 e à 477 e . Give the percentage increase applied to the price of this item. Justify your answer. 13. Unclassified exercises E.1131 A store makes a discount of 15 % on its entire store during the sale period. 1 Help him by telling him how much to multiply the old prices by to make the label change. 2 A television set costs, before discounting, 599 e . What is its price after discounting? 3 After reduction, a DVD player/writer costs 248.2 e . What was its price before discount? https://chingmath.fr chapExoCorrec/7971 sacados/7971 chapExoCorrec/9231 sacados/9231 chapExoCorrec/7924 sacados/7924 Réduction de10%Réduction de32%Augmentation de5%Augmentation de1%px↦−1;05×xpx↦−0;68×xpx↦−0;9×xpx↦−1;01×x chapExoCorrec/4921 sacados/4921 chapExoCorrec/10947 sacados/10947 chapExoCorrec/1131 sacados/1131
12345ABCDEFGx7580859095100 12345ABCDEFGx75808590951009095100105110115420445470495520545405430455480505530 120m60m30m90mABCD(départ)EFGHIJKL E.6281 Pauline’s uncle regularly partic-ipates in a (sailboat race) organized every year on the same stretch of water. In 2012 , he completed the course consisting of two short and three long loops in 8 hours and 40 minutes. When she participated in 2013 , it took her 8 hours and 25 minutes to complete the course consisting of three short and two long loops that year. He remembers that he did not complete any loop in less than 75 minutes. He also knows that it took him 15 minutes longer to run the long loop than it did to run the short loop. However, he wants to know how long it took him to sail the short loop and the long loop on his sailboat. 1 Convert the times achieved for these 2012 and 2013 runs to minutes. 2 Pauline decided, using a spreadsheet, to help her uncle determine the times for the short loop as well as for the long loop. A copy of the resulting screen is given below : She noted x the duration in minutes for the short loop. a What formula for obtaining the time in minutes needed to run the long loop will she enter in cell B2 ? b She will enter in cell B3 the formula ˇ =2*B1+3*B2 ı. What does this formula calculate? c What formula will she enter in cell B4 to calculate the travel time when she attends 2013 ? She then copied the formulas entered in B2 , B3 , and B4 to the right and got the following screen : 3 If she enters the number 105 in cell H1 , what values will she get in cells H2 , H3 , and H4 ? 4 Using the copy of the screen obtained with the spread-sheet, specify the times needed for his uncle to walk the short loop as well as to walk the long loop. E.10836 A professional and an amateur are going to do a karting session on the track below (shown in solid lines) . This track is made up of segments, half circles and quarter circles. The professional makes a lap in 60 seconds. The amateur makes a lap in 72 seconds. 1 Show that the length of the runway is 1 045 m , rounded to the nearest unit. Any trace of research will be valued. 2 Calculate the average speed of the professional in m = s . We’ll round to the nearest hundredth. 3 For safety reasons on this circuit, amateurs must not ex-ceed 60 km = h average speed. Does this amateur respect the safety rules? 4 The professional and the amateur start at the same time from the starting line and complete several laps of the circuit. Recall that the professional completes one lap in 60 s and the amateur in 72 s . a Decompose 60 and 72 into a product of prime factors. b After how long do they find themselves on the starting line together for the first time? c How many laps will they each have completed by then? E.1130 In metropolitan France, in 2001 the pop-ulation was 60.9 million while in 1950 there were 42 million inhabitants . What was the percentage increase in population between these two dates? (round to the nearest tenth) https://chingmath.fr chapExoCorrec/6281 sacados/6281 12345ABCDEFGx7580859095100 12345ABCDEFGx75808590951009095100105110115420445470495520545405430455480505530 chapExoCorrec/10836 sacados/10836 ex 5 polynesie juin 2023 120m60m30m90mABCD(départ)EFGHIJKL chapExoCorrec/1130 sacados/1130