Fast Food Wait Times

[skyguy]

Suppose it is known that the time spent by customers in a fast-food restaurant is a normally distributed variable with a mean of 25 minutes and a standard deviation of 8 minutes. What is the probability that a random sample of 20 customers will yield a mean between 23 and 28 minutes, inclusive?

 

[galactus]

Do you have any idea?.

Use the sample distribution of the sample mean.

\(\displaystyle \L\\\frac{x-{\mu}}{\frac{\sigma}{\sqrt{n}}}\)

Use x=23 and 28. Find their probabilities and subtract them.

 

[james cook]

first find the propability of between 23 and 28 then turn it into a binomial with n=20