In 1999, the average charge for tax preparation by H&R Block, Inc. was $84.57. Assuming a normal distribution
and a standard deviationof o = $10, what proportion of H&R Block’s tax preparation fees were.
a. more than $84.57?
b. between $64.57 and $104.57?
c. between $74.57 and $94.57?
d. more than $104.57?
2. For the normal distributiondescribed in Exercise
1, what is the probabilitythat a randomly selected
tax preparation customer would have paid a fee
a. between $70 and $80?
b. under $60? c. over $90?
3. It has been reported that households in the West
spend an annual average of $6050 for groceries. Assume
a normal distribution with a standard deviation of
a. What is the probability that a randomly selected Western
household spends more than $6350 for groceries?
b. How much money would a Western household have
to spend on groceries per year in order to be at the
99th percentile(i.e., only 1% of Western households
would spend more on groceries)?
4. A random variableis Poissondistributed with
alpha = 0.50 arrivals per minute. For the corresponding exponential
distribution, and x= minutes until the next arrival,
identify the meanof x and determine the following:
a. P(x <or_ 0.5)
b. P( x <or _ 1.5)
c. P( x >or_ 2.5)
d. P( x >or_ 3.0)
This solution determines the proportion of tax preparation fees that H&R Block Inc. will accumulate.