Question

9. If adult male cholesterol is normally distributed with u=200 and o=25; What cholesterol level corresponds to the 75th percentile? TYPE YOUR ANSWER HERE:

Answer 1

Let x = adult mail cholestrol level

Given that x is normally distributed with

Mean $=\mu=200$ and

Standard deviation $=\sigma=25$

we want to find cholestrol level corresponds to 75th percentiles

i.e. $P(Z<z)=0.75$

Where $z =\frac{x-\mu}{\sigma}$

i.e. $P(Z<\frac{x-\mu}{\sigma})=0.75$

By using standard normal table we can calculate the critical value corresponds to probability 0.75

The critical value corresponds to probability 0.75 is 0.674

i.e. $\frac{x-\mu}{\sigma}=0.674$

i.e. $\frac{x-200}{25}=0.674$

i.e. $x=(0.674*25)+200$

we get $x=216.85$ ...............(Answer)