The following data represent the age (in weeks) at which babies first crawl based on a survey of 12 mothers.

52, 30, 44, 35, 47, 37, 56, 26, 35, 35, 52, 52 __________________________________________________________________________
Construct a 95% confidence interval for the mean age at which a baby first crawls. Select the correct choice below and fill in any answers if needed. (choose from one of the below.)

a) (____ , ____)
b) A 95% confidence interval cannot be constructed.

1 answer

95% = mean ± 1.96 SEm

SEm = SD/√n

Find the mean first = sum of scores/number of scores

Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.

Standard deviation = square root of variance

I'll let you do the calculations.

If you can't, then you will have to choose b.