Question

4-30. Micron Technology has sales offices located in four

cities: Dallas, Seattle, Boston, and Los Angeles. An
analysis of the company's accounts receivables reveals
the number of overdue invoices by days, as shown
here.
Days Overdue Dallas
Seattle
Boston
Los Angeles
Under 30 days
30-60 days
61-90 days
Over 90 days
137
85
33
18
122
46
27
32
198
76
55
45
287
109
48
66
Assume the invoices are stored and managed from a
central database.
a. What is the probability that a randomly selected
invoice from the database is from the Boston sales
office?
b. What is the probability that a randomly selected
invoice from the database is between 30 and 90 days
overdue?
c. What is the probability that a randomly selected
invoice from the database is over 90 days old and
from the Seattle office?

Answer 1

An invoice was paid an average of 20 days after it was received.

Mean =

Standard deviation =

Now we are supposed to find what percent of the invoices were paid within 15 days of receipt i.e.P(x<15)

Formula :

At x = 15

Substitute the values

Refer the z table for p value

So, p value = 0.1587

So, 15.87% of the invoices were paid within 15 days of receipt

Explanation: