SOLUTION: The time spent by American adults using their cell phones or computers per day averages 11 hours with a standard deviation of 1.5 hours. The probability that a random sample of 9 A

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Question 929504: The time spent by American adults using their cell phones or computers per day averages 11 hours with a standard deviation of 1.5 hours. The probability that a random sample of 9 American adults averages more than 12 hours is approximately





A 0.9772

B 0.0228

C 0.67

D 0.2514

E 0.7486
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
z+=blue+%28x+-+mu%29%2Fblue%28sigma%2Fsqrt%28n%29%29
z+=blue+%2812+-+11%29%2Fblue%281.5%2Fsqrt%289%29%29 = 2
P(z > 2) = normalcdf(2,100) = .0228
B.