Two hundred fish caught in Cayuga Lake had a mean length of 14.1 inches. The population standard deviation is 2.9 inches. (Give your answer correct to two decimal places.)

Question

Two hundred fish caught in Cayuga Lake had a mean length of 14.1 inches. The population standard deviation is 2.9 inches. (Give your answer correct to two decimal places.) 
(a) Find the 90% confidence interval for the population mean length. 
Lower Limit   
Upper Limit

(b) Find the 98% confidence interval for the population mean length. 
Lower Limit   
Upper Limit

PsyDAG · Answer

a) 90% = mean ± 1.645 SEm SEm = SD/√n b) 98% = mean ± 2.33 SEm

Tom 81 · Answer

I have honestly tried to work this out several times and I just do not see where they are getting the information to use in the formula. Can someone help me.