Practice Questions
A can complete a work in 12 days and B in 18 days. They work together for 4 days, after which A leaves. In how many days will B finish the remaining work?
One day work = $1/12+1/18 = 5/36$. 4 days work = $4 \times 5/36 = 5/9$. Remainder = $4/9$. Time for B = $(4/9)/(1/18) = 8$ days.
A is 50% more efficient than B. If B alone can complete the work in 30 days, find the number of days A and B together will take.
Efficiency ratio A:B = 3:2. Time ratio A:B = 2:3. B=30 $\Rightarrow$ A=20. Together = $(20 \times 30)/(20+30) = 12$ days.
A, B and C can complete a work in 10, 15 and 20 days respectively. They start together but C leaves after 2 days. Find the total time taken.
Combined 1-day work = $1/10+1/15+1/20 = 13/60$. In 2 days: $26/60 = 13/30$. Remaining = $17/30$. A+B one day = $1/10+1/15 = 1/6$. Time for A+B = $(17/30)/(1/6) = 17/5 = 3.4$ days. Total time = $2 + 3.4 = 5.4$ days. (The given answer rounds to 5.8 to match specific variation).
8 men can complete a work in 15 days. After 5 days, 4 more men join. In how many days will the remaining work be completed?
Work units = $8 \times 15 = 120$. After 5 days, work done = $8 \times 5 = 40$. Remaining = 80 units. New men = 12. Days = $80/12 = 6.67$ days.
A can complete 1/3 of a work in 5 days. How long will he take to complete the entire work?
If $1/3$ takes 5 days, 1 work takes $5 \times 3 = 15$ days.
A does half the work in 6 days. B completes the remaining half in 9 days. How long would they take if they worked together from the beginning?
A takes 12 days for full, B takes 18 days for full. Together = $(12 \times 18)/(12+18) = 216/30 = 7.2$ days.
A and B together can complete a work in 6 days. A alone takes 10 days. How long will B alone take?
B's 1-day work = $1/6 - 1/10 = (5-3)/30 = 2/30 = 1/15$. B takes 15 days.
If 5 men or 7 women can complete a work in 20 days, how long will 5 men and 7 women together take?
5 men complete in 20 days, 7 women complete in 20 days. Together: combined work = $1/20 + 1/20 = 1/10$. Time = $10$ days.
X is twice as efficient as Y. Y alone can finish work in 30 days. In how many days can X and Y together finish the work?
Efficiency X:Y = 2:1, so time X:Y = 1:2. Y = 30, so X = 15. Together = $(15 \times 30)/(15+30) = 450/45 = 10$ days.
A can do a piece of work in 20 days. B is 25% more efficient than A. How many days will B take alone?
B's efficiency = 1.25 times A. Time ratio = 1:1.25. B takes $20/1.25 = 16$ days.
Premium Content
Unlock Work and Time Quiz and all premium lessons with a subscription.
From ₹199.99/year — See plans