Grade 7 / Probability 8 exercises (100% corrected)

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123456789101112 1. Equiprobability E.5050 In a raffle, 720 tickets are sold for 2 e . The prizes are provided free of charge by three stores that have agreed to sponsor the project : a portable DVD player, a bread maker, and a mini Hifi system. A student buys 1 ticket. 1 What probability does he have of winning one of the prizes? 2 What probability does he have of winning the mini hi-fi system? E.2649 This exercise is a multiple-choice questionnaire. No justification is required. For each question, three answers are proposed. Only one is correct. Each correct answer earns 1 point. A wrong answer or no answer deducts no points. For each of the three questions, indicate the question number on the copy and copy the correct answer. Statement: A bag contains six balls : four white and two black. These balls are numbered : The white balls are numbered 1; 1; 2 and 3. The black balls have numbers 1 and 2. Question Réponse A Réponse B Réponse C 1 What is the proba-bility of drawing a white ball? 2 3 6 4 4 2 What is the prob-ability of drawing a ball bearing the number 2? 1 4 1 6 1 3 3 What is the prob-ability of drawing a white ball num-bered 1? 1 3 2 4 3 6 E.5108 In a jar with a red lid, we put 6 strawberry candy and 10 mint candy. In a jar with a blue lid, we put 8 strawberry candy and 14 mint candy. The candies are wrapped in such a way that you can’t tell them apart. Antoine prefers strawberry candy. From which jar is he most likely to choose a strawberry candy. Justify your answer. 2. Equiprobability and events E.2639 The next game involves spin-ning the wheel and consider-ing the number and color of the square on which it stops : Determine the probability of the following events : 1 Event A: ˇ the number obtained is 6 ı 2 Event B : ˇ we get a gray box ı 3 Event C : ˇ the number obtained is greater than or equal to 7 ı 4 Event D : ˇ the number obtained is even on a grey square ı 5 Event E : ˇ The number obtained is odd and the square is white ı E.3766 At a fairground booth, a game involves randomly drawing a lottery ticket from a bag contain-ing exactly 180 tickets. 4 of these tickets earn a MP 3 reader. 12 win a large stuffed animal. 36 win a small stuffed animal. 68 allow you to win a key chain. The remaining tickets are loser tickets. What is the probability of a participant : 1 to win a MP 3 drive? 2 win a plush (large or small) ? 3 to win nothing? https://chingmath.fr chapExoCorrec/5050 sacados/5050 chapExoCorrec/2649 sacados/2649 chapExoCorrec/5108 sacados/5108 chapExoCorrec/2639 sacados/2639 123456789101112 chapExoCorrec/3766 sacados/3766 Antilles-Guyane Juin 2009
B226A352LettreCouleurRougeVertBleu 123 3. Probability and two-entry table E.6306 Balls are placed in a bag, all indistinguishable by touch. On each colored ball is written a letter. The following table shows the distribution of the balls : 1 How many balls are in the bag? 2 One ball is drawn at random, and its color and letter are noted. a Verify that there is a one in ten chance of drawing a blue ball with the letter A . b What is the probability of drawing a red ball? c Is it as likely to draw a ball with the letter A as it is to draw a ball with the letter B ? 4. Some examples of non-equiprobability E.7931 At a dartboard game, we use the dartboard below cut into three parts (two right angles are shown) : It is assumed that with each throw of the darts, the arrow lands randomly on the target. We then note the number written in the part hit by the arrow. 1 What is the probability of getting the number 1 ? 2 What is the greater probability, of getting an even num-ber or an odd number? 5. Around the frequency E.5057 Peter rolled a cubic die (not rigged) ten times with faces numbered from 1 to 6 . Each time, he gets 6 . He rolls this die one 11 ième time. What is the probability of getting 6 on the 11 ième throw? https://chingmath.fr chapExoCorrec/6306 sacados/6306 B226A352LettreCouleurRougeVertBleu chapExoCorrec/7931 sacados/7931 123 chapExoCorrec/5057 sacados/5057 Extrait du brevet de Centre Etranger Juin 2009