Question

the length of time it takes to complete a college placement test is normally distributed with a mean of 36 minutes and a standard deviation of 7 minutes. how much time (to the nearest minute) is needed so that 90% of the test takers have time to finish.

Answer 1

To find the amount of time needed so that 90% of test takers have time to finish, standardize the score using the formula z = (x - mean) / standard deviation, find the z-score corresponding to the 90th percentile, and then solve for x.

Step-by-step explanation:

To find the amount of time needed so that 90% of test takers have time to finish, we need to find the value of the score that corresponds to the 90th percentile of the distribution.

First, we need to standardize the score using the formula z = (x - mean) / standard deviation, where x is the raw score, mean is the mean of the distribution, and standard deviation is the standard deviation of the distribution.

Then, we find the z-score corresponding to the 90th percentile using a standard normal distribution table or a calculator. Finally, we use the formula z = (x - mean) / standard deviation to solve for x.

Answer 2

45 min

Step-by-step explanation:

look on z-score table for the value .900

closest on my table is z-score + 1.28

this is 1.28 S.D. above the mean

36 + 1.28 * 7 = ~ 45 min