March 22, 2017

Post a New Question

Posted by on Tuesday, February 15, 2011 at 8:56pm.

A charity believes that when it puts out an appeal for charitable donations the donations it receives will normally distributed with a mean of $50 and standard deviation of $6, and it is assumed that donations will be independent of each other. (i) Find the probability that a sample mean of 5 donations will be smaller than $55. (ii) Find probability that the first donation is at least $3 more than second.

  • statistics - , Wednesday, February 16, 2011 at 11:41am

    Z = (mean1 - mean2)/standard error (SE) of difference between means

    SEdiff = √(SEmean1^2 + SEmean2^2)

    SEm = SD/√(n-1)

    If only one SD is provided, you can use just that to determine SEdiff.

    Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores calculated.

Answer This Question

First Name:
School Subject:

Related Questions

More Related Questions

Post a New Question