Question 705615: Suppose the yearly textbook expenses for a college student are normally distributed with a mean of $850 and a standard deviation of $150.
a) If there are 2,500,000 college students in US as a population, how many students spend more than $1000 for their textbooks?
b) What is the probability that a student spend $700 or less per year
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Suppose the yearly textbook expenses for a college student are normally distributed with a mean of $850 and a standard deviation of $150.
a) If there are 2,500,000 college students in US as a population, how many students spend more than $1000 for their textbooks?
1st:
z(1000) = (1000-850)/150 = 150/150 = 1
P(x > 1000) = P(z > 1) = normalcdf(1,100) = 0.1587
2nd: # that spend more than 1000 = 0.1587*2500,000 is approximately 396639
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b) What is the probability that a student spend $700 or less per year
z(700) = (700-850)/150 = -1
P(x < 700) = P(z < -1) = 0.1587
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Cheers,
Stan H.
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