# What is the z-score of sample X, if n=100,mu=61,St.Dev.=43,and E[X]=98

What is the z-score of sample X, if $n=100,\mu =61,St.Dev.=43,\phantom{\rule{1ex}{0ex}}\text{and}\phantom{\rule{1ex}{0ex}}E\left[X\right]=98$?
You can still ask an expert for help

• Questions are typically answered in as fast as 30 minutes

Solve your problem for the price of one coffee

• Math expert for every subject
• Pay only if we can solve it

Emely English
The z-score for a sample mean is calculated by the formula
$z=\frac{\overline{x}-\mu }{\frac{\sigma }{\sqrt{n}}}$
$\overline{x}=E\left(x\right)=98$
$\mu =61$
$\sigma =43$
$n=100$
Therefore, $z=\frac{98-61}{\frac{43}{\sqrt{100}}}$
$=\frac{37}{4.3}=8.6$