Page 108 - ICSE Math 8

(b) 30 men take 10 days to build a wall. How many days will 25 men take to build the same wall?
(i) 13 (ii) 11 (iii) 12 (iv) 14

(c) x is in inverse variation with y. If x is 8 and the constant of variation is 48, the value of y is:
(i) 9 (ii) 13 (iii) 12 (iv) 6
(d) Pinky bought 15 chocolates for ` 240. Find the cost of 10 chocolates.
(i) ` 160 (ii) ` 155 (iii) ` 150 (iv) ` 165

(e) If p = 4q, then p and q vary ______________ with each other.
(i) inversely (ii) directly
(iii) insufficient information (iv) none of these
2. Fill in the blanks.
x
(a) If two quantities x and y vary in such a manner that is ______________ and ______________,
then x and y are said to be in direct variation. y
5 7
(b) =
15

(c) The time of journey is in ______________ variation with the speed of car.
(d) If xy = 48 and y = 6, then x = ______________.

Time and work, and pipes and cisterns
1. Choose the correct option.

(a) 2 men can do a piece of work in 10 days. How many men are needed to complete the work in 5 days?
(i) 5 men (ii) 8 men (iii) 4 men (iv) 6 men
(b) 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
(i) (ii) (iii) (iv)
5 9 7 6
7
(c) Santosh can do of work in 15 days. With the help of her daughter, Poonam, she completes the
10
remaining work in 4 days. In what time can Santosh and Poonam together do the work?
2 1
(i) 12 days (ii) 12 days (iii) 13 days (iv) 13 days
3 3
(d) 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?
(i) 40 (ii) 45 (iii) 50 (iv) 55
1 1
(e) 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
4 3
work in 13 days. Who will complete the work first?
(i) X (ii) Y (iii) Z (iv) X and Z both
2. Write True or False.
(a) The pipe that fills the tank is called an outlet.
1
(b) If a pipe fills a tank in n hours, then the work done by the inlet in 1 hour is .
n
(c) If 56 men can do some work in 42 days, then 168 men will finish the same work in 12 days.
(d) The work done by the inlet is always positive whereas the work done by the outlet is always negative.

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