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: 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.

Illustration 2 for Class 9 Maths Questions and Ans …

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

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