I don’t like statistics

Question

A botanist wishes to estimate the typical number of seeds for a certain fruit. She samples 70 specimens and counts the number of seeds in each. Use her sample results (mean = 18.7, standard deviation = 6.2) to find the 90% confidence interval for the number of seeds for the species. Enter your answer as an open-interval (i.e., parentheses) accurate to 3 decimal places.  

90% C.I. = 

Answer 1

M = 18.7

Z  = 1.64

s_M  = √(6.2²/70) = 0.74

μ = M ± Z(s_M)

μ = 18.7 ± 1.64*0.74

μ = 18.7 ± 1.219

You can be 90% confident that the population mean (μ) falls between 17.481 and 19.919.

 (17.481, 19.919).