Question

Five students reported the amount of time (in minutes) they spent studying for an AP Statistics test the night before the test. The mean of the reported times is 45 minutes and the standard deviation is 10 minutes.

Answer 1

• a) mean = 60 min
• b) standard deviation = 13.7 min

Explanation:

Question

Five students reported the amount of time (in minutes) they spent studying for an AP Statistics test the night be the test.

• Here are the results: 45 50 60 65 80
• a) Calculate the mean of study times using the formula. Show your work!
• b) Calculate the standard deviation of study time using the table and formula. Show your work!

Solution

Mean of time is:

• x= (45+50+60+65+80)/5 = 60

Deviation >> Square of deviation:

• 45 - 60 = -15 >> 225
• 50 - 60 = -10 >> 100
• 60 - 60 = 0 >> 0
• 65 - 60 = 5 >> 25
• 80 - 60 = 20 >> 400

Sum of squares:

• 225 + 100 + 0 + 25 + 400 = 750

Standard deviation:

• Sx = √750/4 = √187.5 = 13.7