Question

If the diameter of a wire is reduced by 5% then by what percentage should its length be increased so that the rectangles do not change?
a) 12%
b)10.8%
c)11%
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Answer 1

Answer:

Answer is (c) 10.8%

Step-by-step explanation:

Let r be the radius of the cross section of wire and h be its length

Then volume is equal to

$\pi \: r \: {}^{2} h \: \: \: \: \: \: \: \: \: \: \: {i}$

5% of diameter of cross section = 5/100 × 2 r = r/10

New diameter = 2r - r/10

New radius = 19r/20

Let new length be h1....

Volume = pie(19r/20)h1..................................(ii)

From (i) and (ii),

Now in the attachment........ It is given in my pdf of maths.....

I HOPE U WILL GET THE ANSWER............