2. An online bookstore is having a one-day sale. Softcover books are $4, hardcover books are $7, magazines are $3, and all digital downloads of books are $2.

Let's say 150 customers purchased books in one form or another that day. Below are the frequencies in which customers purchased books:

Books: Purchases:
Softcover 42
Hardcover 28
Magazine 23
Digital Download 57
Based on the data above, which is the correct relative frequency with discrete random variable X = "the amount of money for a book?"