Chapter no 13 exercise 13.2full exercise for 8th class
Answers
1. Which of the following are in inverse proportion:
(i) The number of workers on a job and the time to complete the job.
(ii) The time taken for a journey and the distance travelled in a uniform speed.
(iii) Area of cultivated land and the crop harvested.
(iv) The time taken for a fixed journey and the speed of the vehicle.
(v) The population of a country and the area of land per person.
Ans. (i) The number of workers and the time to complete the job is in inverse proportion
because less workers will take more time to complete a work and more workers will take less
time to complete the same work.
(ii) Time and distance covered in direct proportion.
(iii) It is a direct proportion because more area of cultivated land will yield more crops.
(iv) Time and speed are inverse proportion because if time is less, speed is more.
(v) It is a inverse proportion. If the population of a country increases, the area of land per
person decreases.
2. In a Television game show, the prize money of Rs.1,00,000 is to be divided equally
amongst the winners. Complete the following table and find whether the prize money
given to an individual winner is directly or inversely proportional to the number of
winners:
Ans. Here number of winners and prize money are in inverse proportion because winners
are increasing, prize money is decreasing.
When the number of winners are 4, each winner will get = = Rs. 25,000
When the number of winners are 5, each winner will get = = Rs. 20,000
When the number of winners are 8, each winner will get = = Rs. 12,500
When the number of winners are 10, each winner will get = = Rs. 10,000
When the number of winners are 20, each winner will get = = Rs. 5,000
3. Rehman is making a wheel using spokes. He wants to fix equal spokes in such a way
that the angles between any pair of consecutive spokes are equal. Help him by
completing the following table:
(i) Are the number of spokes and the angles formed between the pairs of consecutive
spokes in inverse proportion?
(ii) Calculate the angle between a pair of consecutive spokes on a wheel with 15 spokes.
(iii) How many spokes would be needed, if the angle between a pair of consecutive
spokes is