Question

Q25
Q26 only u can tell me

Answer 1

25) shape of pen just like cylinder
surace area of each pen = surface area of pen = 2πrh

surface area of pen = 2πrh
= 2× 22/7 × (3.5)( 10.5) cm²
= 44 × (0.5) × (10.5) cm²
=22 × (10.5) cm²

total cardboard required for forming 25 pen = 25 × surface area of pen
= 25 × 22 × 10.5 cm²
=5775 cm²

volume of one pen = πr²h = 22/7 × (3.5)²(10.5) = 22× 0.5 × 3.5 × 10.5 cm³
= 404.25 cm³

26) rate of flowing of water = 2.4 km/h
length of water flow in 10minutes = 2.4/60 × 10 = 24/60 = 2/5 = 0.4 km

now , let volume of flowing water just like cuboid
so,
volume of water flowing In the sea at 10 minutes = Length × width × deep
= (0.4 km ) × (3.5 m) × (28m)

= (400 m ) × (3.5 m) × (28 m)

= 2800 × 28 m³

= 78400 m³

so, volume of water In litre = 78400000 litres

Answer 2

Q.25)

Radius = r = 3.5 cm
Height = h = 10.5 cm

Cardboard required to make 1 pen stand = T.S.A of the cylinder

= 2πr (r+h)

= 2 × 22/7 × 3.5 (3.5 + 10.5)

= 2 × 22/7 × 3.5 × 14

= 308 cm²

Cardboard required to make 25 pen stands = 25 × 308

= 7700cm²


Volume of 1 pen stand = πr²h

= 22/7 × 3.5 ×3.5 × 10.5

= 404.25 cm³

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Q.26)


Height = h = 3.5 m

Breadth = b = 28 m

Amount of water flowing in 1 hr = 2.4 km

Amount of water flowing in 60 min = 2.4 km = 2400 metres

Length of the river = l = amount of water flowing in 1 min = 2400/60
= 40 metres

Total amount of water in the river = Volume = lbh


= 40 × 28 × 3.5

= 3920 m³

Amount of water that will fall in 10 min = 39200 m³

1m³ = 1000 litres

39200 m³ = 39200000 litres

Amount of water that will fall in 10 min = 39200000 litres