Question

I WILL GIVE BRAINLIEST!!! A teacher is grading the final exam. He notices that the mean test score is 61, and the standard deviation is 10. The test scores were normally distributed. if there were 450 students in the data sample, how many would have a test score between 61 and 71 *Round your answer to the nearest full value.

Answer 1

Answer:

The number of students that would have a test score between 61 and 71 are 154 students

Step-by-step explanation:

The given information are;

The mean test score, μ = 61

The standard deviation, σ = 10

The sample size, n = 450

The z score is given as follows;

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

We therefore have at x = 61,

$Z=\dfrac{61-61 }{10 } = 0$

P(x > 61) = P(Z > 0) = 1 - 0.5 = 0.5

For x = 71, we  have;

$Z=\dfrac{71-61 }{10 } = 1$

P(x < 71) = P(Z < 1) = 0.84134

The probability that the score will be between 61 and 71 is the difference between the two probabilities, which is 0.84134 - 0.5 = 0.34134

Given that the probability is equivalent to  the proportion of the students that would have a test score between 61 and 71, we have;

The number of students that would have a test score between 61 and 71 = 0.34134 × 450 = 153.6 ≈ 154 to the nearest whole number.