Question

The average summer temperature in Anchorage is 69°F. If the daily temperature is normally distributed with a standard deviation of 7°F, what percentage of the time would the temperature be between 55°F and 76°F?

Answer 1

Answer:

81.85%

Step-by-step explanation:

Given :

The average summer temperature in Anchorage is 69°F.

The daily temperature is normally distributed with a standard deviation of 7°F .

To Find:What percentage of the time would the temperature be between 55°F and 76°F?

Solution:

Mean = $\mu = 69$

Standard deviation = $\sigma = 7$

Formula : $z=\frac{x-\mu}{\sigma}$

Now At x = 55

$z=\frac{55-69}{7}$

$z=-2$

At x = 76

$z=\frac{76-69}{7}$

$z=1$

Now to find P(55<z<76)

P(2<z<-1)=P(z<2)-P(z>-1)

Using z table :

P(2<z<-1)=P(z<2)-P(z>-1)=0.9772-0.1587=0.8185

Now percentage of the time would the temperature be between 55°F and 76°F = $0.8185 \times 100 = 81.85\%$

Hence If the daily temperature is normally distributed with a standard deviation of 7°F, 81.85% of the time would the temperature be between 55°F and 76°F.