Question

The scores of the students on a standardized test are normally distributed with a mean of 500 and a standard deviation of 110 what is the probability that a randomly selected student has a test score between 350 and 550 use the portion of the standard normal cable below to answer the question

A. 7%
B. 9%
C. 59%
D. 91%

Answer 1

the answer is C.) 59 percent

Answer 2

59%

Explanation:

Mean =
`\mu = 500`

Standard deviation =
`\sigma = 110`

We are supposed to find 0 what is the probability that a randomly selected student has a test score between 350 and 550

Formula :
`z = (x-\mu)/(\sigma)`

at x = 350

`z = (350-500)/(110)`

`z =−1.36`

at x = 550

`z = (550-500)/(110)`

`z =0.454`

So, P(-1.36<z<0.454)

P(z<0.45)-P(z<-1.36)

Using z score table

= 0.6736-0.0869

= 0.5867

= 58.6% ≈ 59%

Thus the probability that a randomly selected student has a test score between 350 and 550 is 59%