Question

Select the correct answer. Twenty students in Class A and 20 students in Class B were asked how many hours they took to prepare for an exam. The data sets represent their answers. Class A: {2, 5, 7, 6, 4, 3, 8, 7, 4, 5, 7, 6, 3, 5, 4, 2, 4, 6, 3, 5} Class B: {3, 7, 6, 4, 3, 2, 4, 5, 6, 7, 2, 2, 2, 3, 4, 5, 2, 2, 5, 6} Which statement is true for the data sets?

A. The mean study time of students in Class A is less than students in Class B.
B. The mean study time of students in Class B is less than students in Class A.
C. The median study time of students in Class B is greater than students in Class A.
D. The range of study time of students in Class A is less than students in Class B. E. The mean and median study time of students in Class A and Class B is equal.

Answer 1

B. The mean study time of students in Class B is less than students in Class A.

Explanation:

First step is to calculate the mean and median for both classes.

Class A: 2, 5, 7, 6, 4, 3, 8, 7, 4, 5, 7, 6, 3, 5, 4, 2, 4, 6, 3, 5

sorted data set: 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8

total: 96

# of students: 20

Mean/average: 96 / 20 = 4.8

Median: By looking at the sorted data set, we see that the 10th value is the first 5, so median = 5

Class B: 3, 7, 6, 4, 3, 2, 4, 5, 6, 7, 2, 2, 2, 3, 4, 5, 2, 2, 5, 6

Sorted data set: 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7

Total: 80

# students: 20

Mean/average: 80 / 20 = 4

Median: By looking at the sorted data set, we see that the 10th value is the first 4, so median = 4

So, we can see that the mean study time for group B was less than the students of class A. Answer B.