Question

The pulse rates of adult men approach a normal distribution with a mean of 80 bpm(beats per minute) with standard deviation of 7 bpm. If 60 bpm to 100 bpm is known to be normal. How many percent of the adults have above or below normal pulse rates?

Answer 1

Solution

Population mean $\mu=80$

Standard deviation $\sigma =7$

Percentage above $100$ and below $60$

$Z=\dfrac{X-\mu}{\sigma}$

$Z_{60}=\dfrac{60-80}{7}=-2.86$

$Z_{100}=\dfrac{100-80}7=2.86$

From normal distribution tables

$P(below~ 60) =0.00212$

$P(above~100)=1-0.99788$

$P(above~100)=0.00212$

Total $=0.00424$

Percentage

$=0.00424\times100$

$=0.424\%$