7.12 In 2009, the average charge for tax preparation by H&R Block, Inc. was $187. Assuming a normal distribution and a standard deviation of α= $20, what proportion of H&R Block’s tax preparation fees...

7.12
In 2009, the average charge for tax preparation by H&R Block, Inc. was $187. Assuming a normal distribution and a standard deviation of
α=
$20, what proportion of H&R Block’s tax preparation fees were:

1. more than $187?


2. between $147 and $227?


3. between $167 and $207?


4. more than $227