Question 749078: Psychologists estimate that 80% of male drivers, when lost in trying to find a location, continue to drive rather than asking for directions. If this estimate is correct, what is the probability that, in a random sample of 100 lost male drivers, the proportion who continue to drive is
a) at least 0.70?
b) less than 0.85?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Psychologists estimate that 80% of male drivers, when lost in trying to find a location, continue to drive rather than asking for directions. If this estimate is correct, what is the probability that, in a random sample of 100 lost male drivers, the proportion who continue to drive is
a) at least 0.70?
z(0.7) = (0.7-0.8)/sqrt[0.8*0.2/100] = -2.5
P(x >= 0.7) = P(z >= -2.5) = normalcdf(-2.5,100) = 0.9938
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b) less than 0.85?
z(0.85) = (0.85-0.8)/sqrt[0.8*0.2/100] = 1.25
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P(x < 0.85) = P(z < 1.25) = normalcdf(-100,1.25) = 0.8944
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Cheers,
Stan H.
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