If the base of a rectangular is increased by 10% and the

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If the base of a rectangular is increased by 10% and the area is unchanged , then the corresponding altitude must to be decreased by ?

1. 9¹/₁₁ %
2. 10%
3. 11%
4. 11¹/₉ %

Correct Option: A

Let base = b and altitude = h
Then, Area = b x h

But New base = 110b / 100 = 11b / 10

Let New altitude = H
Then,
Decrese = (h - 10h /11 )
= h / 11

∴ Required decrease per cent
= (h/11) x (1 / h ) x 100 %

= 9¹/₁₁ %