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(10 points) The scores of students on the SAT college entrance examinations at a

ID: 3064768 • Letter: #

Question

(10 points) The scores of students on the SAT college entrance examinations at a certain high school had a normal distribution with mean 531.4 and standard deviation -25.3. (a) What is the probability that a single student randomly chosen from all those taking the test scores 538 or higher? ANSWER For parts (b) through (d), consider a simple random sample (SRS) of 35 students who took the test. (b) What are the mean and standard deviation of the sample mean score , of 35 students? The mean of the sampling distribution for is: The standard deviation of the sampling distribution for is: (c) What z-score corresponds to the mean score of 538? ANSWER: (d) What is the probability that the mean score x of these students is 538 or higher? ANSWER:

Explanation / Answer

a)

( please try 0.3974 if above does not work)

b) mean of sampling distribution for x bar is =531.4

std deviation of sampling distribution for x bar is =25.3/(35)1/2 =4.2765

c)

z score =(538-531.4)/4.2765 =1.5433

d)

( please rtry 0.0618 if above does not work)

for normal distribution z score =(X-)/ here mean=       = 531.4 std deviation   == 25.300