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प्रश्न
An iron pillar consists of a cylindrical portion 2.8 m high and 20 cm in diameter and a cone 42 cm high is surmounting it. Find the weight of the pillar, given that 1 cubic cm of iron weighs 7.5 gm.
उत्तर
Volume of cylindrical portion
`=pir^2h`
`= 22/7 xx (20/2)^2 xx 280`
`= 88000 cm^3`
Volume of conical portion
`=1/3pir^2h`
` =1/3 xx 22/7 xx (10)^2 xx 42`
`=4400 cm^3`
Total number
`= 8800 + 4400`
`=92400`
So total height
`=92400 xx 7.5`
`= 693000 gm`
`= 693 kg`
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Assertion (A)
The curved surface area of a cone of base radius 3 cm and height 4 cm is 15π cm2.\
Reason (R)
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- Assertion (A) is true and Reason (R) is false.
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