Question

The scores for all the sixth graders at Roberts School on a statewide test are normally distributed

with a mean of 76 and a standard deviation of 10.

1. What percent of the scores were below 66

Answer 1

Answer:

15.87%

Explanation:

z-score referred to standard score and it provide idea of the difference from the mean a data point it gives measurement of all standard deviations that falls below as well as above the mean in a given score

we were given:

mean of 76

deviation of 10

To calculate the z- scores

z-score = (the given score of interest - mean score given)/ standard deviation.

Z- score =66 - 76)/10

= -10/10 = -1.

Hence our z- score= -1

The next step is to look up the z-score of -1 on a z-table z-table

if you look for A z-score of -1 on the z- score table you will see that a z- score of (-1) has 15.87% of all scores below it.

Therefore, the percent of the scores that were below 66 is 15.87%

BELOW IS THE ATTACHMENT OF THE Z-SCORE TABLE