The inner circumference of a hollow cylindrical pipe is 4.5 m and the outer circumference is 4.6 m. Find the cost of painting both its inner and outer sides at the rate of rupees 20 per square metre ,if it is 8 m tall
Answers
Step-by-step explanation:
circumference of inner pipe = 2πr = 4.5 m
2 × 22/7 × r = 4.5
r = 4.5 × 1/2 × 7/22
r = 2.25 × 7/22
r = 15.75/22
r = 0.715 m
area of inner surface = 2πhr
= 2 × 22/7 × 8 × 0.715
= 2 × 3.14 × 8 × 0.715
= 2 × 25.12 × 0.715
= 2 × 17.96
= 35.92 sq m
circumference of outer pipe = 2πr = 4.6 m
2 × 22/7 × r = 4.6
r = 4.6 × 1/2 × 7/22
r = 2.3 × 7/22
r = 16.1/22
r = 0.73 m
area of outer surface of pipe = 2 π h r
= 2 × 22/7 × 8 × 0.73
= 2 × 3.14 × 8 × 0.73
= 2 × 25.12 × 0.73
= 2 × 18.33
= 36.66 sq m
area to be painted
= 35.92 + 36.66
= 72.58 sq m
rate of painting Rs. 20/sq m
total cost of painting
= 72.58 × 20
= 1451.6
total cost of painting is Rs. 1451.60
hope you get your answer
Answer: rupees 1456
EXPLANATION:
Outer CSA = . ×=.
Inner CSA = . ×=
Outer CSA + Inner CSA
=.+=.
Cost of painting both sides at the rate of rupees 20 per = 72.8 ×
= rupees 1456