x and y vary inversely such that x = 10 when y = 6. Find the value of y when x = 15.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 4
When x and y vary inversely, one goes up in the same proportion as the other goes down, so their product stays the same: \(xy=k\). The first pair of values gives k, and k then gives the missing value.
The constant from the first pair: \(k=10\times6=60\)
For \(x=15\) the product is still 60: \(15\times y=60\), so \(y=4\)