Question

the sample mean is computed from a random sample of size 25 drama from a population having SD find i)90% ii) 99% confidence interval of the population mean

Answer 1

Sample size $n = 25$

Sample mean $= \bar x$

Sample standard deviation $= s$

$CI = \bar x \pm z \dfrac{s}{\sqrt{n}}$

a.) $CI = \bar x \pm 1.645 \dfrac{s}{\sqrt{n}}$ (z score at 90% = 1.645 )

b.) $CI = \bar x \pm 1.96 \dfrac{s}{\sqrt{n}}$ (z score at 95% = 1.96 )