Have you ever had the experience that driving somewhere seems to take a really long time, but the trip back home goes faster, even though it is the same distance in reverse? Van de Ven et al. (2011) wanted to investigate how common this subjective experience was. They interviewed 69 people who had just been on trips where the outbound and inbound travel time was the same and who had been awake the whole time. They asked the people to evaluate the trips on an 11-point numeric scale, from −5 (return trip was a lot shorter) to +5 (return trip was a lot longer). The data are given below in a frequency table.

a. What is the mean of the return trip time score?

b. Calculate the 95% confidence interval of the mean return trip time score.

c. It is also interesting to know to what extent people experience this subjective impression about travel time in the same way. What is the 95% confidence interval of the variance in the return trip time score?

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Return trip time score -5-5 -4-4 -3-3 -2-2 -1-1 Frequency (number of respondents) 11 44 1111 99 66