Published
1/1t + 1/2t = 3/2t NOT 1/3t. In other words, if it takes Bob 1 hour to clean the pool and Mary 2 hours to clean the pool, then it will take:
1/1t + 1/2t = 1/TOTAL => 1/1 + 1/2 = 3/2 => so we have 3/2 = 1/TOTAL => Simply invert to get the TOTAL... so TOTAL = 2/3 hours.
Another example: If Bob can build a fence in 8 hours, Mary in 12 hours, and Billy in 6 hours, how long will it take them to build a fence together?
1/8 + 1/12 + 1/6 = (3+2+4)/24 = 9/24 = 3/8
So.... 3/8 = 1/TOTAL.... TOTAL = 8/3 (inverting the 3/8). So it take them 22/3 hours to build the fence together.
Here is the formula:
1/(Time taken by A) + 1/(Time taken by B) = 1/(Time taken by A and B together)
Regards,
Chris
dorkypanda
671 Posts
Hi ,
what is the work rate formula ? I've heard we might need to know this equation.
I've searched on the internet and I found two different equations q=rt and 1/ time taken by a + 1/tame taken by b = 1/ time taken by a and b together. Which one is correct?
Thank you