sample of nine students is selected from among the students taking a particular exam. The nine students were asked how much time they had spent studying for the exam and the responses (in hours) were as follows:
18, 7, 10, 13, 12, 16, 5, 20, 21
Estimate the mean study time of all students taking the exam. Round your answer to the nearest tenth of an hour if necessary.
A. 13 hours
B. 12.2 hours
C. 13.6 hours
D. It is not possible to estimate the population mean from this sample data
answer A
A is not correct.
To estimate the mean study time of all students taking the exam, we can calculate the sample mean using the given data. The sample mean is the average of all the observations in the sample.
To find the sample mean, add up all the study times and then divide by the number of students in the sample. In this case, there are 9 students in the sample.
18 + 7 + 10 + 13 + 12 + 16 + 5 + 20 + 21 = 122
Next, divide the sum of the study times by the number of students:
122 / 9 = 13.5556
Rounding to the nearest tenth of an hour, the estimated mean study time is 13.6 hours.
Therefore, the correct answer is C. 13.6 hours.