Lindsay can paint 1/x of a certain room in one hour. If Lindsay and Jo

Hi All,

We're told that Lindsay can paint 1/X of a certain room in 20 minutes - and that Lindsay AND Joseph can paint the FULL room in 1 hour. We're asked what fraction of the same room can Joseph paint in 20 minutes on his own. This question can be solved in a couple of different ways, including by TESTing VALUES.

To start, the math involved would be really easy if BOTH Lindsay and Joseph paint at the same rate. Thankfully, we CAN choose values that will make that happen. If the two work at the same rate, then each will paint 1/2 the room in 1 hour. By extension, in 20 minutes (re: 1/3 of an hour), each would paint (1/3)(1/2) = 1/6 of the room every 20 minutes. Thus, let's TEST X = 6.... meaning that Lindsay paints 1/6 of the room in 20 minutes and Joseph also paints 1/6 of the room in 20 minutes.

We're looking for an answer that equals 1/6 when X = 6. There's only one answer that matches...

Final Answer:

GMAT assassins aren't born, they're made,
Rich