# Class 9 Maths Questions and Answers with Explanation Paper

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__Topic: Surface areas and volumes__

__Class: 9th__

**Q. 1 What is the lateral surface area of a cuboid with dimensions l, b and h.**

Solution.

As we know that a cuboid has six rectangular faces, so its lateral surface area will be the sum of these 6 rectangles.

Lateral surface area of cuboid = Area of rectangle1 + Area of rectangle 2 + Area of rectangle 3+ Area of rectangle 4+ Area of rectangle 5+ Area of rectangle 6

**Q. 2 The Length, breadth and height of a room are 5m, 4m and 3m respectively. Find the cost of whitewashing the walls of the room and the ceiling at the rate of Rs. 7.50 per metre square.**

Sol. **Given**.

Length of room

Breadth of room

Height of room

Area of four walls metre square

Area of ceiling metre square

Total area to be white washed = Area of four walls Area of ceiling

metre square

Cost of whitewashing the room

Cost for 1metre square =Rs. 7.50

Cost for74 metre square

So, cost of whitewashing the walls of room and ceiling is Rs. 555