Problem Solving

Hi lheiannie07,

We're told that Ramon and Jason laid bricks for the 6 walls of a new building together, each of them working alone at a constant rate. Ramon spent 12 FEWER hours laying bricks than did Jason, but Ramon laid bricks at a rate 50% FASTER than did Jason. Each wall required 204 bricks, and the total time it took the two men to complete the job was 84 hours. We're asked for the number of bricks per hour that Ramon laid.

While this is a typical 'table' question - with a lot of information to organize - you can use the patterns involved (and the Answer Choices) to avoid some of the long-winded calculations and still get the correct answer.

To start, Ramon's rate was 50% FASTER than Jason's rate. In these types of questions, it's highly likely that both rates will be INTEGERS, so the correct answer will almost certainly be an integer that is 50% greater than another integer. Only 3 of the 5 answers fit that pattern (24 is 50% greater than 16, 18 is 50% greater than 12 and 12 is 50% greater than 8).

Next, there are 6 walls that require 204 bricks each... that's a total of (6)(204) = 1224 bricks. With 84 hours of total work, we can use some estimation to determine what the AVERAGE brick-laying rate would need to be....

1224/84 = approximately 1200/80 = 15 bricks/hour would need to be laid on average. Now, consider the three 'pairs' of rates from before:
24/hour and 16/hour
18/hour and 12/hour
12/hour and 8/hour

Which pair could have an average of about 15 bricks/hour? Only one option could account for that average - the one that puts Ramon's rate at 18. That also happens to be the correct answer.

Final Answer: C

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

BTGmoderatorDC wrote:Ramon and Jason laid bricks for the six walls of a new building together, each of them working alone at a constant rate. Ramon spent twelve fewer hours laying bricks than did Jason, but Ramon laid bricks at a rate fifty percent faster than did Jason. If each wall required 204 bricks, and the total time it took the two men to complete the job was 84 hours, how many bricks per hour did Ramon lay?

A. 24
B. 22
C. 18
D. 14
E. 12

Is there a strategic approach to this question?

OA C

We are given that Ramon's rate is 50% faster than Jason's rate. If we let Jason's rate = r, then Ramon's rate = 1.5r. We are also given that the total time to complete the job was 84 hours, but Ramon worked 12 fewer hours than Jason did. If we let Jason's time = t, then Ramon's time = t - 12. Let's now determine t:

t + t - 12 = 84

2t = 96

t = 48

So, Jason's time was 48 hours and Ramon's time was 36 hours.

Ramon's work = 1.5r(36) = 54r

Jason's work = 48r

Since total work = Ramon's work + Jason's work, and total work = 6 x 204 = 1224 bricks, we have:

1224 = 54r + 48r

1224 = 102r

12 = r

Thus, Ramon laid 1.5 x 12 = 18 bricks per hour.

Answer: C