Question

The owner of a small convenience store observed that almost all customers paid with credit cards regardless of whether they had cash available, resulting in significant processing charges for the store. The owner began to add a fifty-cent charge to credit card purchases under two dollars, and during the following month, virtually all customers used cash for small purchases while continuing to use credit cards for larger purchases. Nonetheless, during the month after the charge was instated, the average dollar amount of each cash transaction was almost identical to the average dollar amount of each credit card transaction.

The information in the passage most strongly supports which of the following?
A. The average dollar amount spent by customers who did not have cash available was higher after the charge was instated than it had been beforehand.
B. After the charge was instated, customers who used cash for purchases totaling two dollars or more spent more, on average, than customers who used credit cards for these purchases.
C. The average dollar amount spent in each cash transaction at the convenience store was lower after the charge was instated than beforehand.
D. A significant majority of purchases made at the convenience store during the month after the charge was instated were made using credit cards.
E. Prior to the charge, the average amount spent on credit card transactions was higher than the average amount spent on cash transactions.

Answer 1

B. After the charge was instated, customers who used cash for purchases totaling two dollars or more spent more, on average, than customers who used credit cards for these purchases.

Step-by-step explanation:

Since the average transaction remained almost unchanged, that means that customers who used to spend $2 or less are now spending more on average. Assuming that customers that purchase higher amounts didn't change their habits, the only way that the cash purchases equal credit card purchases is that people paying in cash buy more things.

E.g. there are 20 transactions worth more than $2 which are paid using a credit card, so the average transaction is more than $2. In order for cash purchase to have a similar mean, the some transactions will be less than $2 but other transactions must be higher in order to increase the mean of cash purchases: 15 cash transactions worth $1 and 5 cash transactions worth $6, mean cash transaction = $2.25.