Answer: 61.51%
Step-by-step explanation:
To find : percentage for a 20 year old man with a cholesterol level less than 190.
20 lies between 18 and 24.
For this , Cholesterol levels are normally distributed with a mean([tex]\mu[/tex]) of 178 and a standard deviation([tex]\sigma[/tex]) of 41.
let X = cholesterol level in 20 year old man.
Required probability = [tex]P(X< 190)=P(\dfrac{X-\mu}{\sigma}<\dfrac{190-178}{41})[/tex]
[tex]=P(z<0.2926)\ \ \ \ [z=\dfrac{X-\mu}{\sigma}]\\= 0.6151 [\text{By p-value table}][/tex]
hence, the percentage for a 20 year old man with a cholesterol level less than 190 = 61.51%
