Question

A corn cob, shaped like a right circular cone, has the radius of its broadest end as 2.8cm

and Length (height) as 15cm. If each 1cm2

of the surface of the cob carries an average of 5

grains, find the number of grains on the entire cob (Take π =
22/7)

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Answer 1

Please, Don't mind &write the statements on your own

Answer 2

The approximate number of grain present in the entire cob is 671.

Given data :

Radius of the base is 2.8 centimetres.

Height of the corn is 15 centimetres.

In 1cm² area there are 5 grains.

(Now,in the practical life,the grains are always situated in the lateral side of the corn and the base is mostly covered by the stem of the corn.So,we will only focus on the lateral surface area here.)

- At first we have to calculate the slant height of the corn by using the following mathematical formula :

= ✓(radius)²+(height)²

= ✓(2.8)²+(15)²

= ✓7.84+225

= ✓232.84

= 15.25 centimetres (approximately)

So,now we have to calculate the lateral surface area of the corn by using the following mathematical formula :

= π × radius × lateral height

= 22/7 × 2.8 ×15.25

= 134.2 cm²

Now,

1 cm² surface area contains = 5 grains

134.2 cm² surface area contains = 134.2×5 = 671 grains

So,there are approximately 671 grains in that corn. (Answer)