A bus stop is barricaded from the remaning part of the road ,by using 50 hollow cones made of recycled cardboard.Each cone has a base diameter of 40cm and height 1m.If the outer side of each of the cones is to be painted andthe cost of painting Rs12perm2 what will be the cost of painting all these cones.
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Verified answer
Step-by-step explanation:
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
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