Question : A can finish a task in 60 days. He works at it for 15 days and then, B alone finishes the remaining work in 48 days. In how much time can A and B, working together, finish the task?

Option 1: $\frac{960}{31}\ \text{days}$

Option 2: $\frac{171}{37}\ \text{days}$

Option 3: $51\ \text{days}$

Option 4: $45\ \text{days}$

Question : A alone can finish a work in 15 days. A works only for the first two days and the last two days. The rest work is done by B and the work is completed in 20 days. In how many days A and B together can finish the work?

Option 1: $\frac{90}{8}$

Option 2: $\frac{80}{7}$

Option 3: $\frac{80}{9}$

Option 4: $\frac{70}{8}$

Question : Rekha alone can complete a task in 16 days and Bina alone can complete the same task in 12 days. Starting with Rekha, they work on alternate days. The task will be completed in:

Option 1: $12 \frac{3}{4}\ \text{days}$

Option 2: $12\ \text{days}$

Option 3: $13\ \text{days}$

Option 4: $13 \frac{3}{4}\ \text{days}$

Question : A and B together can finish a work in 30 days. They worked on it for 20 days and then B left. The remaining work was done by A alone in 20 days. In how many days can A alone finish the work?

Option 1: 48 days

Option 2: 50 days

Option 3: 54 days

Option 4: 60 days

Question : A is 40% more efficient than B. How much time will they take to work together to complete a job which A alone could have done in 31 days?

Option 1: $\frac{217}{12}\ \text{days}$

Option 2: $\frac{515}{32}\ \text{days}$

Option 3: $\frac{215}{12}\ \text{days}$

Option 4: $\frac{517}{32}\ \text{days}$

Question : A is 40% more efficient than B. How much time will both, working together, take to finish the work, which B alone can finish in 36 days?

Option 1: $18$ days

Option 2: $9 \frac{1}{3}$ days

Option 3: $15$ days

Option 4: $11 \frac{2}{3}$ days