CNNBC recently reported that the mean annual cost of auto insurance is 972 dollars. Assume the standard deviation is 102 dollars. You will use a simple random sample of 58 auto insurance policies. Find the probability that a single randomly selected policy has a mean value between 977.4 and 997.4 dollars. P(977.4 < X < 997.4) =  Find the probability that a random sample of size n=58 has a mean value between 977.4 and 997.4 dollars. P(977.4 < ¯x < 997.4) =  Enter your answers as numbers accurate to 4 decimal places.

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CNNBC recently reported that the mean annual cost of auto insurance is 972 dollars. Assume the standard deviation is 102 dollars. You will use a simple random sample of 58 auto insurance policies.

Find the probability that a single randomly selected policy has a mean value between 977.4 and 997.4 dollars.
P(977.4 < X < 997.4) = 

Find the probability that a random sample of size n=58 has a mean value between 977.4 and 997.4 dollars.
P(977.4 < ¯x < 997.4) = 

Enter your answers as numbers accurate to 4 decimal places.

Expert Solution
Step 1

Let us denote: X=the mean annual cost of auto insurance X follows a normal distribution with mean=972 and standard deviation = 102n=sample size=58X¯ follows a normal distribution with mean=972 and standard deviation =10258=13.3932561517

Step 2

A) The probability that a single randomly selected policy has a mean value between 977.4 and 997.4 dollars is:P(977.4 < X < 997.4) =P977.4-972102<Z<997.4-972102=P(0.0529411764706<Z<0.249019607843)=0.0772

 

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