NCERT Solutions for Class 9 Maths Chapter 13

Important NCERT Questions

Surface Areas and Volumes

NCERT Books for Session 2022-2023

CBSE Board, UP Board and Other state Boards

EXERCISE 13.2

Page No:217

Questions No:11

# The students of a Vidyalaya were asked to participate in a competition for making and decorating penholders in the shape of a cylinder with a base, using cardboard. Each penholder was to be of radius 3 cm and height 10.5 cm. The Vidyalaya was to supply the competitors with cardboard. If there were 35 competitors, how much cardboard was required to be bought for the competition?

Share

Get Hindi Medium and English Medium NCERT Solution for Class 9 Maths to download.

Please follow the link to visit website for first and second term exams solutions.

https://www.tiwariacademy.com/ncert-solutions/class-9/maths/chapter-13/

Radius of each pehholder r = 3 cm and height h = 10.5 cm

The penholder is open at the top, therefore, the area of cardboard for 1 penholder = 2πrh + πr²

= 2 × π × 3 × 10.5 + π × 3² = 63π + 9π = 72π cm²

So, the area of cardboard for 35 penholders = 35 × 72π cm²

= 35 × 72 × 22/7 = 5 × 72 × 22 = 7920 cm²

So, Vidhyalaya has to purchase 7920 cm² cardboard for the competition.