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:

a. more than $187?

b. between $147 and $227?

c. between $167 and $207?

d. more than $227?