AFCAT I 12 Feb 2022 Shift 1 Paper

Let the total work be 40 unit [LCM of 8 & 10]
Efficiency of A=40∕8=5
Efficiency of B=40∕10=4
⇒ Combined efficiency of (A+B)=5+4=9 unit
⇒ Time taken by (A+B) when working together =40∕9
Now, According to the question
⇒ Time taken by C to complete the work =40∕9
⇒ Efficiency of C=40÷(40∕9)=9 unit
Now, We have to find the time taken by B and C
⇒ Combined efficiency of (B+C)=4+9=13 unit
⇒ Time taken by (B+C) to complete the work =40∕13
⇒3‌

1

13

hours.
∴ Time to complete the work by (B+C) together is 3‌

1

13

.