Amateur wrote:

Danny purchased a number of grease pumps of only two possible variants: $5 pumps and $25 pumps. If the ratio between the number of $5 pumps purchased and the number of $25 pumps purchased is 13:7, How many $5 grease pumps did Danny buy?

(1) The total purchase price of the grease pumps Danny bought was less than $400 .

(2) The total purchase price of the grease pumps Danny bought was greater than $200.

Source: HULT

nice question!

suppose we have x pumps that cost 5$ and y pumps that cost 25$.

Danny then spent 5x+25y dollars on the pumps.

we also know that the ratio of x to y is 13:7.

minimum we can have is 13 x pumps and 7 y pumps.

13*5$ = 65$

7*25 = 175$

so minimum spent 240$.

1. total purchase price is less than 400$. only 1 option works... B, C, and E are out.

2. we can have various options...we can have x=13, y=7, or x=26, y=14, etc. not sufficient. D is out.

A is the answer.