Question

The mean of the data set is 40 and one standard deviation is 5. About what percent of the numbers fall between 35 and 50?

Answer 1

Answer:

The correct option is D. 81.8%

Step-by-step explanation:

Mean of the data set is given to be 40

⇒ μ = 40

Standard deviation of the data set is given to be 5

⇒ σ = 5

Now we are supposed to find out what percent of the numbers fall between 35 and 50

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

Now for P(35 < x < 50) :

Substitute x = 35 ⇒ z = -1

Substitute x = 50 ⇒ z = 2

So, P(-1 < z < 2) = P(z < 2) - P(z < -1)

⇒ P(-1 < z < 2) = 0.9772 - 0.1587

⇒ P(-1 < z < 2) = 0.8185

⇒ P(-1 < z < 2) = 81.8%

Therefore, 81.8% percent of the numbers fall between 35 and 50

Hence, The correct option is D. 81.8%