2020 · Q118
A wire of length 6 m is stretched such that its radius is reduced by 20% . Which one of the following is the value of increase in its length?
general-mental-abilityquantitative-aptitude
- A50%
- B56.25%
- C62.25%
- D75%
Explanation
The wire's volume πr²L is conserved: with r → 0.8r, the length becomes L/0.8² = L/0.64 = 1.5625L — an increase of 56.25%.