A cistern 6 m long and 4 m wide contains water up to a depth of 1 m 25 cm. The total area of the wet surface… · ABC26GN4788

Subject: General Aptitude · Chapter: Volume and Surface Area

A cistern 6 m long and 4 m wide contains water up to a depth of 1 m 25 cm. The total area of the wet surface is

(a)$49 \mathrm{m}^{2}$

(b)$50 \mathrm{m}^{2}$

(c)$53.5 \mathrm{m}^{2}$

(d)$55 \mathrm{m}^{2}$

Answer

Answer (as printed): A

Explanation

Area of the wet surface $=[2(l b+b h+l h)-l b]$ $$=2(b h+l h)+l b =[2(4 \times 1.25+6 \times 1.25)+6 \times 4] \mathrm{m}^{2}=49 \mathrm{m}^{2} .$$

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