Question

if A can do as much work in 4hrs as B can do in 6 hrs or as C can do in 8 hrs.They started work together for 1hr after that they work alternately hour by hour starting with A followed by B and C.In how many hours will the total work be finished?​

Answer 1

A's 4 hr work = B's 6 hr work = C's 8 hr work

L.C.M of 4,6,8 = 24= Total work

means

A = 6 unit/hr

B = 4 unit/hr

C= 3 unit/hr

if they work together (A+B+C) = 6+4+3= 13 unit for 1 hr

now remaining work = 24-13= 11 unit

B will work 4 unit in the next 1 hr

remaining = 11-4=7 unit

C will work 3 unit in the next 1 hr

now remaining = 7-3=4 unit

Now A again work to complete 4 unit work.

Because A= 6unit/hr and work= 4 unit remaining

so time taken for this work = 4/6 hr= 2/3 hr

so total time = (1+1+1+2/3) = 3 (⅔) hr

Answer 2

Answer:

_____

Let the tens digit of the required number be x and the units digit be y. Then,

x+y=12 .........(1)

Required Number = (10x+y).

Number obtained on reversing the digits = (10y+x).

Therefore,

(10y+x)−(10x+y)=18

9y−9x=18

y−x=2 ..........(2)

On adding (1) and (2), we get,

2y=14⟹y=7

Therefore,

x=5

Hence, the required number is 57.