钱永强数学课堂上的听课笔记整理-2
18. Each of the following numbers has two digits blotted out. Which of the numbers could be the number of hours in x days, where x is an integer?
(A)25
, 06(B)50
, 26(C)56
, 02(D)62
, 50(E)65
, 20
20. The median score for the class is
(A)76 (B)77 (C)78 (D)79 (E)80
21. If 5 points were added to each score, which of the following would NOT be affected?
(A)The highest score
(B)The mean for all scores
(C)The median for the seniors' scores
(D)The mode for the juniors' scores
(E)The standard deviation for all scores
22. If the mean score for the juniors were known, which of the following could be calculated from the information given?
I. The range of the scores for the seniors
II. The median score for the juniors
III. The mean score for the seniors
(A)None (B)I only (C)III only (D)I and II (E)II and III
23. If in an experiment the probabilities of obtaining the values 
are
, respectively, then the expected value is defined as
For the values and their corresponding probabilities in the table above, what is the expected value?
(A)350 (B)320 (C)300 (D)270 (E)250
24. The standard deviation of the sample The standard deviation of the sample measurements 0, 1, 2, 4, and 8 measurements 0, 1, 3, 5, and 9
25. What is the total number of different 5-digit numbers that contain all of the digits 2, 3,4,7 and 9 and in which none of the even digits occur next to each other?
(A)72 (B)100 (C)120 (D)60 (E)48
Water is to be poured at a rate of 2.5 gallons per minute into a 500-gallon tank that initially contains 50 gallons of water.
28. The percent of the tank's capacity 60 percent
that will be filled 1 hour after water
begins to be poured in
29. In the figure above, if x, y, and z are integers such that x
30. The figure above shows the dimensions of rectangular box that is to be completely wrapped with paper. If a single sheet of paper is to be used without patching, then the dimensions of the paper could be
(A)17 in by 25 in (B)21 in by 24 in (C)24 in by 12 in (D)24 in by 14 in
(E)26 in by 14 in
31. In the table above, what is the least number of table entries that are needed to show the mileage between each city and each of the other five cities?
(A)15 (B)21 (C)25 (D)30 (E)36
32. A store currently charges the same price for each towel that it sells. If the current price of each towel was to be increased by $1, 10 fewer of the towels could be bought for $120, excluding sales tax. What is the current price of each towel?
(A)$ 1 (B)$ 2 (C)$3 (D)$ 4 (E)$ 12
