Page 166 - Start Up Mathematics_8 (Non CCE)

EXERCISE

1. Minti can do a piece of work in 12 days. Minti and Rinki together can finish the work in 8 days.
Find: (a) the number of days in which Rinki alone can finish the work.
(b) the work left if Rinki alone works on it for 4 days.
2. 10 workers earn ` 4,800 in 4 days. What amount will 8 workers earn in 6 days?
3. Arushi and Devesh are making a painting. Arushi can complete the painting in 30 minutes. Both
Arushi and Devesh can complete the painting together in 20 minutes. They work together for 10
minutes and they have a quarrel. At this point, Arushi goes away. In how many minutes will Devesh
finish the painting?
4. Reena can make a doll in 6 days, Meena in 10 days and Kavya in 15 days. Reena and Meena work
for 3 days. How long will it take Meena and Kavya to finish the work?
1
5. Tarun can paint th of a painting in 8 days. How many days will he take to complete the painting?
4
6. 54 girls make 270 garlands in 1 hour. How many garlands will 9 girls make in 3 hours?
1 3
7. A pipe can fill th of the cistern in 16 minutes. In how many minutes, can it fill th of the cistern?
4 4
8. A cistern can be filled by a tap in 7 hours and emptied by an outlet pipe in 9 hours. How long will it
take to fill the cistern if both the tap and the pipe are opened together?

Brainstorming

A rabbit hops in such a way that every time he takes a step towards his destination,
he covers only half the distance left. In how many steps will he reach the carrot field
which is just 50 m away from his burrow?

AT a Glance

Ê 1ˆ
1. If a person X completes a work in n days, then the work completed by him in 1 day is Á ˜ .
n¯
Ë
Ê 1ˆ
2. If a person X completes Á ˜ work in 1 day, then the time taken by him to complete the work is n days.
Ë
n¯
1
3. If a pipe fills a tank/cistern in x hours, then the part of the tank/cistern filled in 1 hour is or the work
1 x
done by the inlet in 1 hour is .
x 1
4. If a pipe empties a full tank in y hours, then the part of the tank emptied in 1 hour is y or the work done
Ê 1 ˆ
by the outlet in 1 hour is - ˜ ¯ .
Á
Ë y

Review Exercises

Multiple ChoiCe Questions

1. 2 men can do a piece of work in 10 days. How many men are needed to complete the work in 5 days?
(a) 5 men (b) 8 men (c) 4 men (d) 6 men

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