Question 1127674: The reading speed of second grade students in a large city is approximately normal, with a mean of 89 words per minute (wpm) and a standard deviation of 10 wpm. Complete parts (a) through (e).
(a) What is the probability a randomly selected student in the city will read more than 93 words per minute?
The probability is
0.3446
(Round to four decimal places as needed.)
(b) What is the probability that a random sample of 13 second grade students from the city results in a mean reading rate of more than 93 words per minute?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The reading speed of second grade students in a large city is approximately normal, with a mean of 89 words per minute (wpm) and a standard deviation of 10 wpm. Complete parts (a) through (e).
(a) What is the probability a randomly selected student in the city will read more than 93 words per minute?
The probability is
0.3446
(Round to four decimal places as needed.)
0.3446 is correct
z(93) = (93-89)/10 = 0.4
Ans:: P(x > 93) = P(z > 0.4) = normalcdf(0.4,100) = 0.3664
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(b) What is the probability that a random sample of 13 second grade from the city results in a mean reading rate of more than 93 words per minute?
z(93) = (93-89)/(10/sqrt(13)) = sqrt(13)*0.4 = 1.4422
Ans: p(x-bar > 93) = P(z > 1.4422) = normalcdf(1.4422,100) = 0.0746
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Cheers,
Stan H.
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