Grade 7 - Mathematics 9.50 Word Problems on Cuboid

Example:
The outer dimensions of a water tank are 6 metres, 5 metres and 4 metres. Find the cost of plastering the outer walls of the tank at the rate of $ 10 per square metre.

Solution:
Given that,
l = 6 metres, b = 5 metres and h = 4 metres. The lateral surface area of the tank = 2h (l+b)
= 2*4 (6 + 5)
= 8 * 11
= 88 square metres.
The cost of plastering the walls at the rate of $ 10 per square metres.
= 88 * 10
= $ 880.

Directions: Read the above example carefully and answer the following questions:

The length of a water tank is 5 more than the width and 3 less than the height. Find the cost of plastering the outer walls of the tank at the rate of $ 6 per square metre.