Question

A2 Statistics Practice (I need help solving questions 5-7)

Answer 1

5. Given a specific value of
`X`, the corresponding
`Z` value is obtained from

`Z=(X-\mu_X)/(\sigma_X)`

You're given
`\sigma_X=17` and that
`z=-1.5` when
`x=250`. This means

`-1.5=(250-\mu_X)/(17)\implies\mu_X=275.5`

6. Same as 3 and 4. I assume you have a calculator you can use to find
`P(z<2.25)`. You should get around 0.9878.

7. We're told that 18.72 is 1.5 standard deviations below the mean of 31.5. This translates to

`18.72=31.5-1.5\sigma_X\implies\sigma_X=8.52`