Bunuel
A newly released book includes hardback and paperback. If the sales price for the hardback is $20, and the sales price for the paperback is $15, what is the average price for all of the books sold during a certain day?
(1) The ratio of the number of the hardback sold to the number of paperback sold is 5 to 3.
(2) A total of 160 books were sold during the day.
Solution: Pre Analysis:- Sale price of hardback \(=$20\)
- Sale price of paperback \(=$15\)
- We are asked the average sale price of all the books sold during a day
Statement 1: The ratio of the number of the hardback sold to the number of paperbacks sold is 5 to 3
- Let the number of hardback to paper sold be \(5x\) and \(3x\) respectively
- Sale price of \(5x\) hardbacks \(=20\times 5x=100x\)
- Sale price of \(3x\) paperbacks \(=15\times 3x=45x\)
- Average sale price =\(\frac{\text{Total sale pirce}}{\text{Total books sold}}=\frac{100x+45x}{5x+3x}=\frac{145x}{8x}=\frac{145}{8}\)
- Thus, statement 1 alone is sufficient and we can eliminate options B, C and E
Statement 2: A total of 160 books were sold during the day
- This information gives us no information on the number of paperback and hardback sold
- Average sale price \(=\frac{\text{Total sale pirce}}{\text{Total books sold}}=\frac{\text{Total sale pirce}}{160}\)
- Thus, statement t2 alone is not sufficient
Hence the right answer is
Option A