Time and Work

• Time and work problems can be solved using unitary method.
• More persons will do more work in same time.
• More persons will take less time to do the same work.
• Remuneration is based on the amount of work done, which is in direct proportion to speed of work. If three persons can separately do a job in 3, 4, 5 days respectively, then remuneration will be divided in ratio 1/3 : 1/4 : 1/5.

Exercise

1. Ramdin can reap a field in 30 days. What part of the field would he have reaped in 25 days?
2. If 12 men working 8 hours a day can construct a shed in 5 days, then in how many days will 8 men working 10 hours a day complete the same job?
3. Three ants separately can gobble a dead grasshopper in 3, 4 and 6 days respectively. How many days will they take together to finish off the poor chap? If the grasshopper weighs 63 grams, find the share of each.
4. If a chicken and a half lays an egg and a half in a day and a half, how long does it take to get a dozen eggs from a chicken?
5. A dozen pens cost 15 rupees. How much would a hundred pens cost?
6. 400 grams cake costs 80 rupees. How much would a 1.5 kg cake cost?
7. It rained 80 mm in first 20 days of April. What would be the total rainfall in April?
8. 50 grams of fish food is sufficient for 8 fish for a day. How much would 12 fish require in a day?
9. 50 grams of fish food is sufficient for 8 fish for a day. On the same amount of food, for how many days can 2 fish survive?
10. A man builds a chair in 4 days, working 6 hours a day. How many hours should he work in a day if he wants to do it in 3 days instead of 4 days?
11. Four men working together take 3 hours to paint a wall. How much time would 6 men take to do the same job?
12. A man earns Rs 18000 in 3 months.
    (a) How much time would he take to earn Rs 30000?
    (b) How much will he earn in 7 months?
13. Ram can build a table in 6 days while Shyam requires 8 days for the same work. Working together,
    (a) how many days would they require to construct 7 tables?
    (b) how many tables can they construct in 48 days?
14. A man and a woman working together can sow a field in 20/9 days. The man alone can do it in 4 days. How much time would the woman working alone take to sow the field?

Answers