A surprising fact is that 66% of all teens have a TV set in their room. If a pol

Question

A surprising fact is that 66% of all teens have a TV set in their room. If a poll chooses a simple random sample of 1000 teens and asks if they have a TV set in their room, the percent who say "Yes" will vary if the sample is repeated. In fact, the percent "Yes" in many samples (of the same size) will follow a normal distribution with mean 66% and standard deviation 1.5%. What is the probability of taking a sample and observing a sample proportion less than 62.25%? 0.0062 0.0668 0.5000 0.9332 0.9938

Explanation / Answer

Mean ( u ) =0.66
Standard Deviation ( sd )=0.015
Normal Distribution = Z= X- u / sd ~ N(0,1)                  
P(X < 0.6225) = (0.6225-0.66)/0.015
= -0.0375/0.015= -2.5
= P ( Z <-2.5) From Standard Normal Table
= 0.0062                  

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