Question

IF the diameter of the cross section of a wire is decreased by 5% how much% will the length be increased so that its volume remains same

Answer 1

diametre be d
radius be d/2
vol=πr*r*h
    =πd*d*h/4
if d is  increased by 5% then d- 5%of d
d-5/100*d
d-d/20
19d/20
∴r=2*19d/20=19d/40
vol=πd*d*h/4
π*19d/40*19d/40*h
∴h=400d/361 ( calculate the above one)
increase in length=400h/361-l
=39l/361
%of increase =39h/361/h*100=3900/361% =10.80%

Answer 2

heya..

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