Question

Q. The floor of a rectangular hall has a perimeter 250 m. If the cost of painting the four walls at the rate of ` 10 per m2 is ` 15000, find the height of the hall

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Answer 1

✯ According To Question :

• ➥ Base perimeter = 2×(l+b) = 250 m

✯ Used Formula :

• ➥ Total area painted = L.S.A

• ➥ Total Money spent on painting / Rate of painting 1 m ²

✯ Concept Behind :

• ➥ For calculating height of Hall we have to just apply one formula Total Money spent on painting / Rate of painting 1 m ² . We can easily Calculate height of Hall

✯ Putting Value in Formula :

• ➼ 15000 / 10  = 1500 m ²

• ➼ L.S.A = 2 × (l+b) × h

• ➼ 250 × h = 1500 m²

• ➼ h = 1500 ÷ 250

• ➼ 6 m

☯ Therefore :

★ Height of Hall is 6 Meter ★

_____________________________

Answer 2

Answer:

Given:

Perimeter=250m

⇒Area of 4 walls =2lh+2bh

=2(b+l)h

⇒Perimeter of floor of wall =2l+2b

⇒2(l+b)=250 m

∴ Area of 4 walls =2(l+b)h

=250h m

2

⇒Cost of painting per m

2

area = Rs. 10

⇒Cost of painting 250h m

2

area = Rs(250h×10)

= Rs.2500h

⇒Painting cost of walls = Rs. 15000

⇒2500h=15000

⇒h=

2500

15000

⇒h=6m