Question

If n=15. (x-bar)=50, and s=9, construct a confidence interval at a 80% confidence level. Assume the data came from a normally distributed population. Give your answers to one decimal place. <μ<

Answer 1

If the data is normally distributed, then for a small sample size (<30) , confidence intervals for mean $\mu$ is obtained by using student's t-distribution with (n-1) d.f.

If the data is normally distributed then for small sample size, confidence interval for mean is geven by (ł - t. 2 h + d ) - wo where, & us level of significance. Here, we are given n=15, n=56, s=9 we have to calculate 80% confidence level that means a= 0.2 (20% level of significance) using table, we get tore 1.345 betting these valus in abot at 80%. confidence level, confidence interved for Mis (50-1.345x 2 CM < 50+ 1.345 X 11 ) J145 46.9 CMC 58.1]