Question

A alone can do a piece in $10$ days and $B$ alone can so it in $15$ days. In how many days will $A$ and $B$ together do the same work?

• A. $5$ days
• B. $6$ days
• C. $8$ days
• D. $9$ days

Answer 1

The correct option is B $6$ days

We know that,
Number of days $A$ required to do piece of work $=10$ days

Number of days $B$ required to do piece of work $=15$ days

$\therefore$ We can calculate, work done $A$ in $1$ day $=1/10$

Work done by $B$ in $1$ days $=1/15$

Now, work done by both $A$ and $B$ together in $1$ day $=1/10+1/15=10/60=1/6$

$\therefore A$ and $B$ can do work together in $6$ days