Answer: 60 customers
To find the number of customers who charge their purchases, we can set up a ratio table based on the information given.
Let's assume the number of customers who charge their purchases is represented by "C" and the number of customers who pay cash is represented by "P."
According to the given information:
For every 11 customers who pay cash (P), 4 customers charge their purchases (C).
There are 165 customers who use cash for their purchases.
Now, let's set up the ratio table:
Customers Paying Cash (P) Customers Charging (C)
Quantity 11 4
Number 165 C
To find the value of "C," we can use proportions. Since the ratio of customers paying cash to customers charging is constant, we can set up a proportion:
(11 customers paying cash) / (4 customers charging) = (165 total customers paying cash) / (C total customers charging)
11/4 = 165/C
Now, we can cross-multiply to solve for C:
11C = 4 * 165
11C = 660
Finally, divide both sides by 11 to find the value of C:
C = 660 / 11
C = 60
So, there are 60 customers who charge their purchases at the bookstore.