KSEEB Solutions for Class 7 Maths Chapter 11 Perimeter and Area Ex 11.3

KSEEB Solutions for Class 7 Maths Chapter 11 Perimeter and Area Ex 11.3

Karnataka State Syllabus Class 7 Maths Chapter 11 Perimeter and Area Ex 11.3

Question 1.
Find the circumference of the circles with the following radius :
(Take n = 22/7)
a) 14 cm
radius = r = 14 cm
∴ circumference of a circle = 2πr

Question 14.
A circular flower garden has an area of 314 m². A sprinkler at the centre of the garden can cover an area that has a radius of 12 m. Will sprinkler water the
entire garden? (Take π = 3.14)
Solution:
Area of the circular flower garden = 314 sq.m
Radius of the sprinkler = 12m
Area of the sprinkler = πr² = 3.14 × 12 × 12
= 452.16 sq.mt
∴ 452.16 > 314
∴ Yes, the sprinkler water the entire garden.

Question 15.
Find the circumference of the inner and the outer circles, shown in the adjoining figure? (Take π = 3.14)
Solution:

Circumference of the outer circle = 2πr
radius = 19 m
= 2 × 3.14 × 19
= 119.32 mts
Circumference of the inner circle = 2πr
radius = 19 – 10 = 9 cm.
= 2 × 3.14 × 9
= 56.52 cm

Question 16.
How many times a wheel of radius 25cm must to go 352 m ? (Take π = 22/7)
Solution:
radius of the wheel = r = 28 cm
circumference of the wheel = 2πr

= 176 cms
To cover the distance of 352 mtrs (∵ 1 m = 100 cm)
No. of rotation

Question 17.
The minute hand of a circular clock is 15 cm long. How far does the tip of the minute hand move in 1 hour? (Take π = 3.14)
Solution:
Length of the minute hand = 15 cm
1 hour = 1 round = circumference = 2πr
= 2 × 3.14 × 15
= 94.2 cms
∴ The tip of the minute hand in one hour moves 94.2 cms.