Question

Which of these are examples of Direct Variations?
(i) Cost price to grocery
(ii) Time required in completing a work to number of workers doing that work
(iii) Distance covered to time when speed is constant

• A. (i), (ii)
• B. (i), (ii), (iii)
• C. (i), (iii)
• D. (ii)

Answer 1

The correct option is C (i), (iii)

Two quantities are said to be in direct variations if increase in one quantity causes an increase in the other and vice-versa.
If, however, increase in one quantity causes a decrease in the other and vice-versa, then the two quantities are said to be in indirect variations.

Based on this, let's check for each example given.
(i) The cost price for a grocery increases as the amount of it increases and vice-versa. So, these two quantities vary directly.
(ii) Work can be done in less time when more workers do the same work and vice-versa. So, these two quantities vary indirectly.
(iii) Keeping the speed constant, as the time is increased, the distance covered increases and vice-versa. So, these two quantities vary directly.
So, (i) and (iii) are the examples of direct variations.