Question
The radii of two solid right circular cylinders are 4 cm
and 3 cm respectively and their heights are (h+1) cm and (2h+1) cm respectively. If the areas of the whole surface of the two cylinders are equal, then the ratio of their volumes is:Solution
Whole surface area of cylinder = 2Ï€R(H+R) 2Ï€ x 4[h+1+4] = 2Ï€ x 3[2h+1+3] 4[h+5] = 3[2h+4] 4h+20 = 6h+12 2h = 8 h = 4 so, V1/V2 = (Ï€ x 42 x (h+1))/(Ï€ x 32 x (2h+1)) Â Â Â Â Â = (16 x (4+1))/(9 x (2x4+1)) Â Â Â Â Â = (16 x 5)/(9 x 9) Â Â Â Â Â = 80/81
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