The sum and difference of the slant height and height of cone A are in the ratio 3 ∶ 1, while the sum and difference of the slant height and height of cone Y are in the ratio 5 ∶ 1. If the volume of cone A is 30% of the volume of cone B, then the height of cone A is what percentage of the height of cone B.
The sum and difference of the slant height and height of cone A are in the ratio 3 ∶ 1, while the sum and difference of the slant height and height of cone Y are in the ratio 5 ∶ 1. If the volume of cone A is 30% of the volume of cone B, then the height of cone A is what percentage of the height of cone B. Correct Answer 50%
Given:
Sum and difference of the slant height and height of cone A are in the ratio 3 ∶ 1
Sum and difference of the slant height and height of cone Y are in the ratio 5 ∶ 1
Volume of cone A is 30% of the volume of cone B
Formula used:
Volume of cone = (1/3) πr2h
Calculation:
Let the radius, slant height and height of cone A be r, l and h units respectively
Given, (l + h)/(l – h) = 3
⇒ l + h = 3l – 3h
⇒ 2l = 4h
⇒ l = 2h
For cone A, l2 = h2 + r2
⇒ (2h)2 = h2 + r2
⇒ 3h2 = r2
⇒ Volume of cone A = (1/3) πr2h = (1/3) π × 3h2 × h = πh3 cubic units
Similarly,
Let the radius, slant height and height of cone B be ‘R’, ‘L’ and ‘H’ units respectively
Now, (L + H)/(L – H) = 5
⇒ L + H = 5L – 5H
⇒ 4L = 6H
⇒ L = 3H/2
For cone B, L2 = H2 + R2
⇒ (3H/2)2 = H2 + R2
⇒ 9H2 = 4H2 + 4R2
⇒ 5H2/4 = R2
⇒ Volume of cone B = (1/3) πR2H = (1/3) π × 5H2/4 × H = (5/12) πH3 cubic units
Now,
Volume of cone A = 30% of volume of cone B
⇒ πh3 = (3/10) × (5/12) πH3
⇒ h3/H3 = 1/8
⇒ h/H = 1/2
∴ Height of cone A is 50% of the height of cone B