Question

A 5 m wide cloth is used to make a conical tent of base diameter 14 m and
height 24 m. Find the cost of cloth used at the rate of < 25 per metre

Answer 1

First find l
l²=h²+b²
l² = (24)²+(7)²
l² = 576+49
l² = 625
l = 25 m

so curved surface area of conical tent
= π×r ×l
=22×7×25/7
=22×25
=550 m²

1 sq m: 550 sq m :: ₹25: ?₹
=550 × 25
=13750

so total cost of tent 13750 rupees

Answer 2

Radius of base (r) and height (h) of the conical tank are 7 m and 24 m
⇒ Slant height (l) = r 2 + h 2
                            =  (7 m) 2 + (24 m) 2
                            = 49m 2 + 576m 2
                            = 625m 2
                            = 25m
Thus,
Curved surface area = πrl =  22 7 × 7 × 25 m 2 = 550m2

Now let x m of cloth is rquired
Then C.S.A of conical tank = area of cloth

⇒ 5x = 550
⇒ x =  550 5 = 110

Hence 110m of cloth is required to make the required conical tank.