Question

7. (1) If the volume of a cylinder of height 7 cm is 448 7 cm”, find its lateral surface
area and total surface area.
(ii) A wooden pole is 7 m high and 20 cm in diameter. Find its weight if the wood
weighs 225 kg per m².
Mensuration
397
DXD​

Answer 1

Answer:

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Step-by-step explanation:

volume of cylinder=πr²h

 πr²h=448π

r²h=448

7r²=448

r²=448/7

r²=64

r=8cm

CSAof cylinder=2πrh

                       =2X22/7X8X7

                       =352 cm²

TSA=2πr(h+r)

  

     =2X22/7X8(15)

    

     =352/7X15

 

     =754.28cm²

ii)length of pole is 7m

and diameter of pole = 20cm = 0.2 m

so, the radius of pole = 0.1m

now, volume of pole = volume of cylinder = πr²h

= 22/7 × 0.1 × 0.1 × 7

= 22 × 0.01

= 0.22 m²

now, weight = volume × density

here given,

density = 225 Kg/m³

volume of pole = 0.22 m³

now, weight = 225 × 0.22

= 49.5 Kg

hence, weight of pole = 49.5 Kg

Answer 2

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