Question

At Stephanie's new job, she spent $6.50, $8, $7.25, $13.50, and $9.75 on lunch the first week. In the second week, Stephanie spent a total of $10 less than the total of the first week. What is the decrease in the mean for the second week compared to the first week?

answer as a decimal rounded to the nearest hundredth.

Answer 1

The mean for the second week is $2 less than the first and in percentage it is 22% less.

Explanation:

The mean is given by the sum of all individual values divided by the number of values. For the first week the sum is:

sum1 = 6.5 + 8 + 7.25 + 13.5 + 9.75

sum1 = 45

Since she spent 10 less in the second week the sum is:

sum2 = sum1 - 10 = 45 - 10 = 35

The mean for each week is:

mean1 = sum1/5 = 45/5 = 9

mean2 = sum2/5 = 35/5 = 7

difference = mean1 - mean2 = 9-7 = 2

difference(%) = [2/9]*100 = 0.22*100 = 22%

The mean for the second week is $2 less than the first and in percentage it is 22% less.