CBSE Class 8 Mathematics Direct and Inverse Proportions Assignment Set A

Fill in the blanks :

Question. Ratio a/b remain _________ in direct Variation.
Answer : Constant

Question. ab is constant in __________ variation
Answer : Inverse Variation

Question. Which of the following quantities do not vary directly with each other.
(i) Distance travelled (at constant speed) and petrol used.
(ii) Ages of boys and their weight
(iii) Area of land and its price.
(iv) Number of pages of a book and its price.
(v) Number of men available and time taken to do a job.
Answer : (ii) and (v)

Question. Raghav takes 75 steps to cover a distance of 50 m. How much distance will he cover in 375 steps.
Answer : 250 m

Question. 20 pumps can empty a reservoir in 12 hours. In how many hours can 45 such pumps do the same work?
Answer : 5(1/3) Hours

Question. The minimum speed for passing a typing test is 40 words per minute. How many words should an examinee type in half an hour so as to pass the typing test?
Answer : 1200

Question. A machine takes 5 hours in cutting 120 tools. How many tools will it cut in 20 hours.
Answer : 480

Question. 36 books are packed in 2 carton of the same size. How many such cartons will it require to pack 144 books?
Answer : 8 cartoons

Question. If 15 stamps of a denomination occupy an area of 60 sq. cm. How much area of paper is required for putting 120 stamps assuming that no area is wasted in between the stamps
Answer : 480 cm²

Question. Which of the following vary inversely to each other?
(i) The number of labourers engaged to dig a trench and time to complete thedigging.
(ii) The length of journey by train and price paid for the ticket.
(iii) The number of subjects and time to do the home work in each subject.
(iv) Speed of vehicles and time taken to cover a fixed distance.
Answer : (i) and (iv)

Question. Rita can finish a work in 9 days. How much work she do in 2 days.
Answer : 2/9

Question. If 6 men can complete the wiring of a house in 7 days. In how many days 21 men can do this work.
Answer : 2 days

Question. Two trains 500m and 700m long are going with speeds 70km/hr. and 50km/hr. respectively in opposite direction. How long will it take to pass each other.
Answer : 36 sec.

Question. If the 45 men can do a work in 20 days. Then how many men can do the same work in 75 days.
Answer : 12 Days

Question. A contractor employs a work force of 500 persons to complete construction of a bridge in six months. If he is asked to complete the work in 4 months then how many extra persons will he have to employ.
Answer : 250

Question. x and y are inverse quantities. If the value of x is 15 and value of y is 5 then which pair is not corresponding to x and y.
(i) 25 and 3 (ii) 14 and 5
(iii) 16 and 6 (iv) 18.75 and 4.
Answer : (ii), (iii)

Question. If 10 men can do a work in 8 days then in how many days 2 men can do this work.
Answer : 40 Days

Question. The speed of a car is 90km/hour. What is its speed in m/sec.?
Answer : 25 m/sec.

Question. A train of length 315m is travelling at a speed of 54 km/hour. In what time will it pass a pole?
Answer : 21sec

Click on link below to download CBSE Class 8 Mathematics Direct and Inverse Proportions Assignment Set A