SSC CGL 20 Aug 2021 Shift 2 Paper

Question : 61 of 100

Marks: +1, -0

The volume of a wall whose height is 10 times its width and whose length is 8 times its height is

51.2

{m}^{3}

. What is the cost (in

₹

) of painting the wall on one side at the rate of

₹ 1000 \/ {m}^{2}

Solution:

Let the width of wall

=b {m}

Then height of wall

=10 {b} {m}

and length of wall

=10 {b} × 8=80 {bm}

Given volume of wall

=51.2 {m}^{3}

⇒ \;\; I × b × h=51.2

⇒ \;\; 80 b × b × 10 b=51.2

⇒ \;\; 800 b^{3}=51.2

⇒ \;\; b^{3}=\;{512}/{8000}

⇒ \;\; b=\;{8}/{20}=\;{2}/{5} m

=l × b=80 b × b=80 × b^{2}

=80 × \;{4}/{25}=12.8 {m}^{2}

∴

Required cost

=12.8 × 1000

= ₹ 12800

Go to Question:

Prev Question

Next Question