Question

3
19. Case study based
To develop a critical and analysing skills amongs
t her children, math teacher
showed her students a video of 3d objects and asked the students to identify 3d
'objects. One such video was of PWD workers constructing road using road
roller. The cylindrical road roller made of iron was 1.2m long. Its diameter
was 56cm.
d. 132cm
i. What is the circumference of the cylindrical road roller?
a. 176cm
b. 88cm
c. 44cm
ii. What is the curved surface area of road roller?
b. 6.245m2 c. 2.112m2
Page 4 of 10
a. 4m2
d. 0.176m2
iii. If it takes 500 revolutions what is the total area covered
a. 31252m2
b. 1056m²
c. 88m2
d. 2000 m
iv. If it covers 1250m² what will be the cost of rolling at Rs 25 per m??
a. Rs 31,250 b. Rs 22,900 c. Rs 15,550 d. Rs 19,550
v. Formula for total surface area of cylinder
a. CSA + 2 x circumference
c. CSA + area of circle


b. CSA + circumference
d. CSA + 2 x area of circle​

Answer 1

Answer:

Step-by-step explanation:

The cylindrical road roller made of iron was 1.2m long. Its diameter

was 56cm

(a)  What is the circumference of the cylindrical road roller?

2πr

= 2× 22/7× 28

= 175.84

= 176 cm (approx)

(b) What is the curved surface area of road roller?

2πrh

= 2× 22/7× 28× 120

= 21100.8 cm

= 211.008m

(c)  If it takes 500 revolutions what is the total area covered

1 revolution = lateral surface area

500 revolution = 500× 21100.008

= 105500,004

= 1056 m²

(d)  If it covers 1250m² what will be the cost of rolling at Rs 25 per m?

CSA of roller = 1250 / 211.008

= 5.923 revolution