Problems on time and work part 6

Q. 1. A completes a work in 12 days and B complete the same work in 24 days. If both of them work together, then the number of days required to complete the work will be(a) 8 (b) 6 (c) 7 (d) 5 (e) None of theseAns: (a) 8Explanation:If A can complete a work in x days and B can complete the same work in y days, then, both of them together can complete the work in x y/ x+ y days.Therefore, here, the required number of days = 12 × 24/ 36 = 8 days. Ans.Q. 2. If 4 men can colour 48 m long cloth in 2 days, then 6 men can colour 36 m long cloth in(a) 1 day (b) 1 ½ days (c) ¾ day (d) ½ day (e) None of theseAns: (a) 1 dayExplanation:The length of cloth painted by one man in one day = 48 / 4 × 2 = 6 mNo. of days required to paint 36 m cloth by 6 men = 36/ 6 × 6 = 1 day. Ans.Q. 3. If 3 persons can do 3 times of a particular work in 3 days, then, 7 persons can do 7 times of that work in (a) 7 days (b) 6 days (c) 4 days (d) 3 days (e) None of theseAns: (d) 3 days.Explanation:That is, 1 person can do one time of the work in 3 days.Therefore, 7 persons can do 7 times work in the same 3 days itself. Ans.Q. 4. Mangala completes a piece of work in 10 days, Raju completes the same work in 40 days. If both of them work together, then the number of days required to complete the work is(a) 15 (b) 10 (c) 9 (d) 8 (e) None of theseAns: ( d) 8Explanation:If A can complete a work in x days and B can complete the same work in y days, then, both of them together can complete the work in x y/ x+ y days.That is, the required No. of days = 10 × 40/50 = 8 days. Ans.Q. 5. 12 men work 8 hours per day to complete the work in 10 days. To complete the same work in 8 days, working 15 hours a day, the number of men required(a) 4 (b) 5 (c) 6 (d) 8 (e) None of theseAns: (d) 8Explanation:That is, 1 work done = 12 × 8 × 10Then, 12 8 × 10 = ? × 15 × 8? (i.e. No. of men required) = 12 × 8 × 10/15× 10 = 8 days. Ans.