SOLUTION: A random sample of size n = 72 is taken from a population with mean μ = −13.7 and standard deviation σ = 9. [You may find it useful to reference the z table.]
a. Calcul
Algebra ->
Probability-and-statistics
-> SOLUTION: A random sample of size n = 72 is taken from a population with mean μ = −13.7 and standard deviation σ = 9. [You may find it useful to reference the z table.]
a. Calcul
Log On
Question 1162677: A random sample of size n = 72 is taken from a population with mean μ = −13.7 and standard deviation σ = 9. [You may find it useful to reference the z table.]
a. Calculate the expected value and the standard error for the sampling distribution of the sample mean. (Negative values should be indicated by a minus sign. Round "expected value" to 1 decimal place and "standard error" to 4 decimal places.)
b. What is the probability that the sample mean is less than −14? (Round “z” value to 2 decimal places, and final answer to 4 decimal places.)
c. What is the probability that the sample mean falls between −14 and −13? (Do not round intermediate calculations. Round "z" value to 2 decimal places and final answer to 4 decimal places.)
You can put this solution on YOUR website! E(X)= -13.7, the mean
SE is sigma/sqrt(n)=9/sqrt(72)=1.0607
z<(-14--13.7)/1.0607
<-0.3/1.0607
<-0.28. or -0.2828
probability is 0.3897
z for -13 is (0.7/1.0607)=0.6600
probability of z between -0.28 and 0.66 is 0.3567
