NIELIT Scientific Assistant A 2020 November: 33

Question

Ram can do a piece of work in $5$ days, and Sham can do the same in $10$ days. With the help of Karan, they finished the work in $2$ days. How many days would it take Karan to do the work?

• A. $5$ days
• B. $10$ days
• C. $15$ days
• D. $20$ days

Answer 1

Given that, $R \quad S \quad K$

Time$: \qquad5 \quad 10 \quad x\quad $ (days)

Total work $: LCM(5,10,x) = 50x$ unit.

Efficiency$: 10x \quad 5x \quad 50$

We know that, $\text{Total work =  Efficiency $\times$ Time}$

$\implies 50x = (15x + 50) \times 2$

$\implies 50x = 30x + 100$

$\implies 20x = 100$

$\implies x = 5$ days.

So, the correct answer is $(A).$

Answer 2

solution