What is answe to #12 and #13? Assume that the heights of men are normally distri

Question

What is answe to #12 and #13? Assume that the heights of men are normally distributed with mean 71.1 inches and a standard deviation of 3.4 inches. If 81 men are randomly selected from this population, what is the standard error of the mean? (round to two decimal places) At a cell phone assembly plant, 82% of the cell phone keypads pass inspection. A random sample of 170 keypads is analyzed. Find the probability that less than 85% of the sample keypads pass inspection A) .8200 B) .8324 C) .8023 D) .8461 The GPA of the graduating seniors of a certain university is normally distributed with a mean of 3.2 and standard deviation of 0.32. At a special honors convocation, students whose GPAs are at the top 2% are to be given special recognition, what is the minimum GPA a student needs to receive recognition? The distribution of the math portion of SAT scores are normally distributed with a mean of 500 and a standard deviation of 100. Determine the scores that make up the middle 90% of all SAT scores. (Round answers to the nearest ten)

Explanation / Answer

(12)
mean = 3.2
std. dev. = 0.32

For 2%, z-value = 2.05
xbar = mean + z*sigma
xbar = 3.2 + 2.05*0.32
xbar = 3.856

Hence 3.856 is the minimum GPA a student needs to receive recognition.

(13)
mean = 500
std. dev. = 100

z-value for the respective 5% at both tails is +/- 1.96

lower limit = 500 - 1.96*100 = 304
upper limit = 500 + 1.96*100 = 696

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