Question

A bus stop is barricaded from the remaining part of the road, by using 50 hollow
cones made of recycled cardboard. Each cone has a base diameter of 40 cm and height
1 m. If the outer side of each of the cones is to be painted and the cost of painting is rupees
12 per m
what will be the cost of painting all these cones? (Use π = 3.14 and take
V1.04 = 1.02)​

Answer 1

Answer: Radius of the cone (r) = 40/2 cm = 20 cm = 0.2 m

Height of the cone (h) = 1 m

Let l be the slant height of a cone.

∴ l = √h2 + r2

⇒ l = √12 + 0.22

⇒ l = √1.04

⇒ l = 1.02 m

Rate of painting = ₹12 per m2

Curved surface of 1 cone = πrl m2

= (3.14 × 0.2 × 1.02) m2

= 0.64056 m2

Curved surface of such 50 cones = (50 × 0.64056) m2

= 32.028 m2

Cost of painting all these cones = ₹(32.028 × 12)

= ₹384.34

Step-by-step explanation:

Answer 2

Answer:

cost

Curved surface area of cone will be painted=πrl

h=1m;radius=

2

40

=20cm=0.2m

and let l be the slant height,

∴l

2

=h

2

+r

2

=1

2

+0.2

2

⇒l=

1+0.04

=

1

.04=1.02m (∵

1

.04=1.02 is given in the question)

⇒Curved surface area of 1 cone=πrl=(3.14×0.2×1.02)m

2

=0.64046m

2

⇒ Curved surface area of 50 cones=50×0.64046=32.028m

2

Cost of painting 1m

2

=Rs.12

∴ Cost of painting 32.028m

2

=(12×32.028)=384.336m

2

≈384.34

∴ Cost of painting 50 cones is Rs.384.84