Question

The ratio of circumference and area of a circle is 2:7. Find its circumference.Choose the correct alternative answer for the following question.
A) 14π
(B) 7/π
(C) 7π
(D) 14/π

Answer 1

Answer - Option (A). 

Solution -
Area of the Circle (A) = πr²
Circumference of the Circle (C) = 2πr

Ratio of the C to A = 2:7
∴ 2πr/πr² = 2/7
⇒ 2/r = 2/7
∴ r = 7 

∴ Circumference of the Circle  = 2πr
 = 2π (7)
 = 14π 


Hence, Option (A) is correct.


Hope it helps.

Answer 2

SOLUTION:-

GIVEN BY RATIO:-
circumference:area = 2 : 7
$area = \pi {r}^{2} \\ circumference \: = 2\pi \: r \\ according \: to \: question \\ \frac{2\pi \: r}{\pi {r}^{2} } = \frac{2}{7} \\ \frac{1}{r} = \frac{1}{7} = r = 7 \\ circumference \: (2\pi {r}^{2} ) \\ 2\pi \times 7 = 14\pi$
hence,your right answer is option (A) 14π

■I HOPE ITS HELP■