Please solve question number 12 to 16 help me please tomorrow is my exam note that question only for jishnu Mukherjee
Answers
Question 12
Radius of the small circle
C = 2 π r
= > 44 = 2 π r
Take π as 22 / 7
= > 22 = π r
= > 22 / 7 r = 22
= > r = 7 × 22 / 22
= > r = 7 m
Radius of bigger circle = 7 + 3.5
= 10.5
Area of path
Area of path = Area of big circle - area of small circle
= > π R² - π r²
= > π ( R² - r² )
= > π ( 10.5² - 7² )
= > π ( 10.5 + 7 )( 10.5 - 7 )
= > π × 17.5 × 3.5
= > 61.25 × 22/7
= > 1347.5 / 7
= > 192.5 m²
Cost
Rs 20 is required for 1 m²
For 192.5 m² money required = 192.5 × 20
= > Rs 3850
ANSWER :
Rs 3850
Question 13
Let thickness of the metal be h .
Volume = 56 cm × 33 cm × h
= > 1848 h
Volume of disc = π r² h
= > V = 22 / 7 × 7 × 7 × h
= > V = 154 h
Number of discs = 1848 h / 154 h
= > 12
ANSWER :
12 discs can be made .
Question 14
Area of circle = 308 / 2 cm² = 154 cm²
= > π r² = 154 cm²
= > 22 / 7 r² = 154
= > r² = ( 154 × 7 ) / 22
= > r² = 7 × 7
= > r = 7
Length of rectangle = 2 × diameter
= > 2 × 14 cm
= > 28 cm
Breadth = diameter = 2 × 7 cm
= 14 cm
Perimeter = 2 ( l + b )
= > 2 ( 28 + 14 )
= > 2 × 42
= > 84 cm
ANSWER :
84 cm is the perimeter .
Question 15
Area of big semicircle = 1/2 × π r²
= > 1/2 × 22/7 × ( 14/2 )²
= > 1/2 × 22/7 × 7²
= > 1/2 × 22 × 7
= > 11 × 7
= > 77
Area of small semi-circle = 1/2 × 22/7 × ( 7/2 )²
= > 11 / 7 × 49 / 4
= > 77 / 4
Area of shaded portion
= > 77 - 77 / 4
= > 77 - 19.25
= > 57.75
ANSWER :
57.75 cm²
Question 16
Area of shade = Area of big circle - ( area of small circles )
= > π R² - ( π r² + π r² )
= > π ( 21/2 )² - ( π ( 14/2 )² + π ( 7/2 )² )
= > 441 / 4 π - ( 196 / 4 π + 49 / 4 π )
= > 441 / 4 π - 245 / 4 π
= > 196 / 4 π
= > 22 / 7 × 49
= > 22 × 7
= > 154 cm²
ANSWER :
154 cm²