Question

A can do a piece of work in 14 days while B cando it in 21 days. they began together and worked for 7 days. then, A fell ill and B had to complete the work. in how many days was the work completed?​

Answer 1

Step-by-step explanation:

A can do in one day = 1/14 of the work

B can do in one day = 1/21 of the work

They can do work together in seven days = 1/14 + 1/21 = 3+2/42 = 5/42

5/42 * 7 = 5/6 of the work

Left work = 1-5/6 = 1/6 of the work

No. of days in which B will complete the work = Remaining work / B's one day work = 1/6/1/21 = 7/2 = 3 days 12 hours.

So, the work was completed in 7 + 3.5 = 10.5 days

Answer 2

Answer:

let b work speed be 3x and a work speed be 2x for x is 7

here

here we can see the speed of b is 33% slower

so for 7 days consider a work which is done in 14 days

half it means 50% done. now consider b speed

for 55/33×10

we see that 66.666% work is done when 33% work is remaining. now since b has to do 33.3% of the work we will take 33.3% of b work which is 21÷3 since 100÷3=33.3

which comes 7 days

. means they both work together for 7 days and b work for next 7 days which means they worked for tital 7+7 which is 14 days