Question

Question 62

In questions which of the following vary directly and which vary inversely with each other and which are neither of the two?
(i) The quantity of rice and its cost.
(ii) The height of a tree and the number of years.
(iii) Increase in cost and number of shirts that can be purchased, if the budget remains the same.
(iv) Area of land and its cost.
(v) Sales tax and the amount of the bill.

Answer 1

(i) The quantity of rice and its cost are directly proportional to each other.
e.g. Let 1 kg of rice price =Rs 40
Then, 2 kg of rice price =Rs $2\times 40=Rs80$
(ii) The height of a tree and the number of years are neither directly nor inversely proportional to each other.
(iii) Increase in cost and number of shirts that can be purchased, if the budget remains the same are inversely proportional to each other.
e.g. Let 2 shirts price =Rs 800
After increasing in price of each shirt,
1 shirt price became Rs 800
where budget =Rs 800
(iv) Area of land its cost are directly proportional to each other.
e.g Let $200m^2$ land cost Rs 5000
Then $400m^2$ land cost =Rs 10000
Sales tax and the amount of the bill are directly proportional to each other.
e.g. Let bill amount =Rs 1000
Sales tax =10%
Then, sales tax $=\frac{10}{100}\times 1000$=Rs 100
But if bill amount =2000
Sales tax =10%
Then, sales tax $=\frac{10}{100}\times 2000=10\times 20=Rs200$