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Probability

Question
CBSEENMA9003402

Find:

(ii)    how much steel was actually used if of the steel actually used was wasted in making the tank?

Solution

(ii) Total surface area = 2 πr space left parenthesis straight h space plus straight r right parenthesis
    equals 2 cross times 22 over 7 cross times 2.1 cross times left parenthesis 4.5 plus 2.1 right parenthesis
equals 2 cross times 22 over 7 cross times 2.1 cross times 6.6 equals 87.12 space straight m squared

Let the actual area of steel used be x m2.
Since 1/12 of the actual steel used was wasted, the area of the steel which has gone into the tank = 11/12 of x.
therefore space space space space 11 over 12 straight x equals 87.12
therefore space space space space space straight x equals fraction numerator 87.12 cross times 12 over denominator 11 end fraction equals 95.04 space straight m squared
therefore   Steel actually used = 95.04 m2