Quantitative Aptitude Ques 378

Question: Base of a prism of height 10 cm is square. Total surface area of the prism is $ 192,cm^{2}. $ The volume of the prism is

Options:

A) $ 640,cm^{3} $

B) $ 160,cm^{3} $

C) $ 90,cm^{3} $

D) $ 120,cm^{3} $

Show Answer

Answer:

Correct Answer: B

Solution:

  • Height of prism = 10 cm Let the side of square be a cm, Total surface area of prism $ =192,cm^{2} $ Now, Perimeter of base $ \times $ Height + 2 $ \times $ Area of base = 192

$ \Rightarrow $ $ 4a\times 10+2\times a^{2}=192 $

$ \Rightarrow $ $ 40a+2a^{2}=192 $

$ \Rightarrow $ $ 2a^{2}+40a-192=0 $

$ \Rightarrow $ $ a^{2}+20a-96=0 $

$ \Rightarrow $ $ a^{2}+24a-4a-96=0 $

$ \Rightarrow $ $ a,(a+24)-4,(a+24)=0 $

$ \Rightarrow $ $ (a-4)(a+24)=0 $

$ \therefore $ $ a=4cm^{2} $

$ \therefore $ Volume of prism = Area of base $ \times $ Height $ =4\times 4\times 10=160,cm^{3} $