Question

please explain by steps! very confused

10) The average charitable contribution itemized per income tax return in Pennsylvania is $792. Suppose that the distribution of contributions is normal with a standard deviation of $103. Find the limits for the middle 60% of contributions.

Answer 1

10. Here distribution is normal with mean=792 and standard deviation=103

Now we need to find x1 and x2 such that

Pxl < X < x2) = 0.60

Pxl < X < x2) = 0.60

Using z table we get

P(-0.842<:<0.842) = 0.60

So we have

21 - v1 – H = -0.842

So

rl = -0.842 * O +=(-0.842 * 103) +792 = 705.274

And

x2 = 0.842 * 0 +u = (0.842 * 103) +792 = 878.726