A botanist wishes to estimate the typical number of seeds for a certain fruit. S

Question

A botanist wishes to estimate the typical number of seeds for a certain fruit. She samples 39 specimens and counts the number of seeds in each. Use her sample results (mean 299, standard deviation-10.6) 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 one decimal place (because the sample statistics are reported accurate to one decimal place). 90% C.1. Answer should be obtained without any preliminary rounding.

Explanation / Answer

Ans:

Given that

sample size,n=39

sample mean=29.9

sample standard deviation=10.6

df=39-1=38

critical t value=tinv(0.1,38)=1.686

standard error of mean=10.6/sqrt(39)=1.697

90% confidence interval for population mean

=29.9+/-1.686*1.697

=29.9+/-2.9

=(27.0, 32.8)

*(as n>=30,we can also use z multiplier=1.645,then answer will be (27.1,32.7))

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