# Class 9 Maths Questions and Answers with Explanation Paper (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Topic: Surface areas and volumes**

**Class: 9 ^{th}**

**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 ₹ 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 = ₹ 7.50
- Cost for74 metre square
- So, cost of whitewashing the walls of room and ceiling is ₹ 555