If x and y vary inversely with each other and x = 7 when y = 12, then find y when x = 21.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 4
When two quantities vary inversely, their product stays constant: as one grows, the other shrinks in the same ratio.
The constant product, from the given pair: \(xy=7\times12=84\)
When \(x=21\), \(y\) is this product divided by 21: \(\displaystyle y=\frac{84}{21}=4\)