Question

During a certain week the mean price of gasoline in the New England area was $2.815 per gallon . A random sample of 34 gas stations is drawn from this population . What is the probability that the mean price for the sample was between $2.766 and \$2.920 that week ? Assume sigma=\$0.43

Answer 1

the sample mean is normally distributed with mean u and standard deviation, then

`z=\frac{x-\mu}{\frac{\sigma}{\sqrt[]{n}}}=\frac{2766-2815}{\frac{0.43}{\sqrt[]{34}}}=-664.46`

and

`z=\frac{2920-2815}{\frac{0.43}{\sqrt[]{34}}}=1423.84`

so,

[tex]P(2766answer: 94.11%