1、GRE（ QUANTITATIVE）综合模拟试卷 13及答案与解析 0 A group of 20 values has a mean of 85 and a median of 80. A different group of 30 values has a mean of 75 and a median of 72. (a)What is the mean of the 50 values? (b)What is the median of the 50 values? 3 In how many different ways can the letters in the word STU
2、DY be ordered? 4 Martha invited 4 friends to go with her to the movies. There are 120 different ways in which they can sit together in a row of 5 seats, one person per seat. In how many of those ways is Martha sitting in the middle seat? 5 How many 3-digit positive integers are odd and do not contai
3、n the digit 5 ? 6 From a box of 10 lightbulbs, you are to remove 4. How many different sets of 4 lightbulbs could you remove? 6 A talent contest has 8 contestants. Judges must award prizes for first, second, and third places, with no ties. (a)In how many different ways can the judges award the 3 pri
4、zes? (b)How many different groups of 3 people can get prizes? 8 If an integer is randomly selected from all positive 2-digit integers, what is the probability that the integer chosen has (a)a 4 in the tens place? (b)at least one 4 in the tens place or the units place? (c)no 4 in either place? 11 In
5、a box of 10 electrical parts, 2 are defective. (a)If you choose one part at random from the box, what is the probability that it is not defective? (b)If you choose two parts at random from the box, without replacement, what is the probability that both are defective? 14 Find the mean and median of t
6、he values of the random variable X, whose relative frequency distribution is given in the table below. 14 Eight hundred insects were weighed, and the resulting measurements, in milligrams, are summarized in the boxplot below. (a)What are the range, the three quartiles, and the interquartile range of
7、 the measurements?(b)If the 80th percentile of the measurements is 130 milligrams, about how many measurements are between 126 milligrams and 130 milligrams? GRE（ QUANTITATIVE）综合模拟试卷 13答案与解析 1 【正确答案】 mean = 79 2 【正确答案】 The median cannot be determined from the information given. 3 【正确答案】 5! = 120 4 【正确答案】 24 5 【正确答案】 288 6 【正确答案】 210 7 【正确答案】 336 8 【正确答案】 56 9 【正确答案】 1/9 10 【正确答案】 1/5 11 【正确答案】 4/5 12 【正确答案】 4/5 13 【正确答案】 1/45 14 【正确答案】 mean = 2.03, median = 1 15 【正确答案】 range = 41, Q1= 114, Q2= 118, Q3= 126, interquartile range = 12 16 【正确答案】 40 measurements
