1、GRE（ QUANTITATIVE）练习试卷 16及答案与解析 1 If you roll a single 6-sided die, what is the probability that you will roll an odd number? 2 A company knows that 2.5% of the CD players it makes are defective. If the company produces 300,000 CD players, how many will be defective? 3 When flipping a coin, what is
2、the probability that it will land on tails four times in a row? 4 If the probability that Dave will go to class is 0.7, what is the probability that he will not go to class? 5 A bowl contains 20 marbles (8 blue, 6 red, 3 green, 2 yellow, and 1 orange). If you reach in and choose one marble at random
3、, what is the probability that it will be red? GRE（ QUANTITATIVE）练习试卷 16答案与解析 1 【正确答案】 On a 6-sided die, there are 3 even numbers, and 3 odd numbers. Therefore, the probability that you will roll an odd number is 3 out of 6, or 3/6. This can be reduced to 1/2, or 0.5. 2 【正确答案】 If 2.5% of the CD play
4、ers produced by this company are defective, then the number of defective devices out of 300,000 can be determined by multiplication, as follows: 0.025300,000=7,500 3 【正确答案】 When flipping a coin, there are only two possible outcomes: heads or tails. Therefore, each side has a probability of 1/2, or 0
5、.5, of landing facing up. The chances of the coin landing on tails four times in a row can be expressed as 4 【正确答案】 The probability that Dave will go to class is 0.7, or 70%. Therefore, the probability that he will NOT go to class is 100%-70%, or 30%, which is equivalent to 0.3, so either answer will be correct. 5 【正确答案】 There is a total of 20 marbles in the bowl, 6 of which are red. If one marble is selected at random, the probability that it will be red is This can be reduced to 3/10
