Mathematics Homework Help

USA
Today reported that the state with the longest mean life span is Hawaii, where
the population mean life span is 77 years. 
A random sample of 20 obituary notices in the Honolulu Advertizer had a
mean of  = 71.4
years and a standard deviation, s = 20.65 yrs. 
Assuming that life span in Honolulu is approximately normally
distributed , does this information indicate that the population life span for
Honolulu residents is less than 77 years? 
Use a 5% level of significance.