Page 167 - Start Up Mathematics_8 (Non CCE)

2. A can finish a work in 18 days, B can do the same work in half the time taken by A. Working together,
what part of the same work can they finish in a day?
2 1 2 1
(a) (b) (c) (d)
5 9 7 6
3. Santosh can do 7 of work in 15 days. With the help of her daughter, Poonam, she completes the remaining
10
work in 4 days. In what time can Santosh and Poonam together do the work?
2 1
(a) 12 days (b) 12 days (c) 13 days (d) 13 days
3 3
4. 10 computer operators can type 120 pages in 2 hours. How many operators should work if the job is to
be completed in 30 minutes?
(a) 40 (b) 45 (c) 50 (d) 55
1 1
5. X can do th of a work in 10 days, Y can do 40% of the work in 15 days and Z can do of the work
4 3
in 13 days. Who will complete the work first?
(a) X (b) Y (c) Z (d) X and Z both

solve Mentally

True or False
1. The pipe that fills the tank is called an outlet.
1
2. If a pipe fills a tank in n hours, then the work done by the inlet in 1 hour is .
n
3. If 56 men can do some work in 42 days, then 168 men will finish the same work in 12 days.
4. The work done by the inlet is always positive whereas the work done by the outlet is always negative.

Fill in the Blanks
1. Time is ____________ proportional to work.
-1
2. If an outlet empties a full tank in __________ hours, then work done by it in 1 hour is .
n
3. If Neha knits 35 scarves in 25 days, she will take __________ days to knit 55 scarves.
1
4. If Murshid can do a piece of work in 20 days, he can do of the work in _________ days.
5
Answer in One Word or a Line
1. 3 men or 5 women can construct a wall in 12 days. Will 6 men and 5 women take longer to construct the
wall?
2. Soni can do a piece of work in 6 days, Moni can do it in 4 days and Noni can do it in 12 days. What will
be their 1 day’s work, if they work together?
3. A tap can fill a cistern in 8 hours and another tap can empty the full cistern in 16 hours. What will be the
time taken to fill the cistern if both the taps are open?

let’s evaluate
1. Rinku can knit a sweater alone in 6 hours and Seema can knit a sweater alone in 8 hours. How much time
would they take working together to knit (a) 1 sweater, (b) 14 sweaters.
1 1
2. Manoj can weave rd of a saree in 5 days and Karan can weave th of the same saree in 6 days. If they
3 4
work together, in how many days will the work be completed? Also find who is more efficient?

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