A can do a job in 12 hours. B can do the same job
in 16 hours. A does a part of work and leaves the
rest for B. If A works for 9 hours, how many hours
will it take B to finish the remaining job?
Answers
Answer:
A = rate of A = 1/12 of the job in 1 hour.
B = rate of B = 1/16 of the job in 1 hour.
A * (1/12) * 12 = 1 means A takes 12 hours to complete 1 job.
B * (1/16) * 16 = 1 means B takes 16 hous to complete 1 job.
A * 9 = (1/12)*9 = 9/12 means A completes 9/12 of the job in 9 hours.
1 - 9/12 = 3/12 means 3/12 of the job remains to be done.
B * x = 3/12 means B will complete 3/12 of the job in x hours.
x = (3/12) / B means divide both sides of the equation by B to solve for x.
x = (3/12) / (1/16) means dividing by B is the same as dividing by (1/16)
x = (3/12) * (16) means dividing by (1/16) is the same as multiplying by 16.
x = (3 * 16) / 12 means (3*16)/12 is equivalent to (3*16)/12.
x = 16 / 4 means simplify the expression.
x = 4 means solve for x to get the answer.
It will take B 4 more hours to complete the job.
That's a total of 9 + 4 = 13 hours.
9 * (1/12) + 4 * (1/16) = (9/12) + (1/4) = (3/4) + (1/4) = 1 means confirm the answer is good by carrying out the complete calculation with the solved value for x.
9/12J =
Answer:
A can do the job in 12 hours means A completes 100% in 12 hours
so in One hour , A completes (100/12 )% of job
Now.B completes 100% in 16 hrs ==> B completes (100/16)% in one hour .
Given A works for 9 hours ==> 9/12 =>( 3/4)*100 ==> 75 % of job is done.
Now 1/4 of the job is to be done by B ==> 1/4*16==> 4 hours.
So B can finish the work in 4 hrs