A corn cob, shaped somewhat like a cone, has the radius of its broadest end as 2.1 c m and length (height) as 20 c m . If each 1 c m 2 of the surface of the cob carries an average of four grains, find how many grains (approximately) you would find on the entire cob.Submitted on 23/12/2023 | Answered by Vandana Rana

Answer :

We know, the curved surface area of cone cob = πrl
Given, r=2.1cm,h=20cm
Now, slant height l²=(r²+h²) =(2.1)²+(20)²
⟹l= √404.41 =20.11cm
∴ Curved surface area of corn cab =
22/7×2.1×20.11 =132.73cm².
Since, the number of grains on 1cm²of the surface corn cob =4
∴ Number of grain on 132.73cm² of the surface of corn cab =132.73×4
=530.92 ≈531 .