Working together

I got D too

Jacks time for me was 6 hours and Toms was 12 hours

D

By solving 1 Tom timing is 6 and that of Jack is 12. however, not able to solve with second and getting calculation error

1/T + 1/J = 1/4 (1)
1/2T + 1/J = 1/3 (2)

Solving 1 & 2
1/T - 1/2T = 1/4 -1/3 = -ive (not possible ) . Please suggest.

JeffB wrote:I got D too

Jacks time for me was 6 hours and Toms was 12 hours

Ok, solution is 6 for Jack. I am messing up somewhere. For the below statement, can you provide your equation and solution?

Jack is painting twice as fast as Tom.

For me, J = 2T (I am guessing here is where I am missing)

1/J + 1/T = 1/4

1/2T + 1/T = 1/4

3/2T = 1/4, hence T = 6, hence J = 12

Where am I going wrong?

@crackgmat007:

Both working together have a speed of 1/4 wall/hour.

If you define J and T as wall/hour, then

1/4 = J + T (not 1/J, 1/T)

From stml. 1 we know that J = 2T, hence T = J/2.

1/4 = J + J/2 => J = 1/6 wall/hour

It takes J 6 hours to complete a wall.

T = J/2 => T = 1/12

It takes T 12 hours to complete a wall.

Hope that helps.

Btw. I chose (D), too.

Got it...thanks much.