4.) * 5p
2
In Mrs. Chapman's math class, of the students got
either an A or a B on the last test. Of these students,
got a B. What fraction of the class got a B on the last
test?
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step- i d k and i d c : )

you: : 0

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8

step-by-step explanation:

just put √(2) * √(32) into a calculator. that will make the answer be 8.

ratio is 2 : 9

the answer is three

13.5 : 3

irst, find the z score of a score of 80. this is given by the formula z = (x-u)/o, where x is the score, u is the mean, and o is the standard deviation. this gives

z = (80-78)/12 = 1/6 = .1667

now, find what percentile a z score of 1/6 correlates to in the normal distribution.

a z score of 1/6 = .1667 is equivalent to the 56.36th percentile of the distribution. so the probability a score is over this is 1-.5636 = .4364

the mean of a sample mean is equal to the original mean. however, the standard deviation of a sample mean is equal to the original standard deviation divided by the square root of n (sample size). so the new standard deviation is 12/sqrt(16) = 3.

the new z score is 80-78/3 = 2/3 = .667. this is equivalent to the 74.86th percentile. so the probability that the mean will be greater than this score is 1-.7486 = .2514.