A college professor stops at McDonalds every morning for 10

A college professor stops at McDonald\'s every morning for 10 days to get a number 1 value meal costing $5.39. On the 11th day he orders a number 8 value meal costing $4.38.

Which of the following are true?
Select all that apply.

Select one or more:

1) During the first 10 days the professor\'s standard deviation was more than 0.

2) During the first 10 days the professor\'s standard deviation was less than 0.

3) During the first 10 days, the professor\'s standard deviation was 0.

4) It is impossible to tell anything about the professor\'s standard deviation for the first 10 days.

5) Considering all 11 days, the professor\'s standard deviation was lower than the standard deviation of the first 10 days.

6) Considering all 11 days, the professor\'s standard deviation was higher than the standard deviation of the first 10 days.

7) Considering all 11 days, the professor\'s standard deviation was the same as the standard deviation of the first 10 days.

8) Considering all 11 days, It is impossible to tell anything about the professor\'s standard deviation compared to the first 10 days.

Solution

3) During the first 10 days, the professor\'s standard deviation was 0.

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6) Considering all 11 days, the professor\'s standard deviation was higher than the standard deviation of the first 10 days.