Question

If the radius of a circle is increased by 3 times. Then, what percent ( or percentage ) of new area will be more than the old one.


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Answer 1

Original radius = r

Original area = πr^2

or

$\pi {r}^{2}$

Now, the new radius = 3 × r = 3r

New area =

$\pi {(3r)}^{2} = \pi9 {r}^{2} = \frac{198}{7} {r}^{2}$

Percentage increase = Original value/New value × 100

$\frac{\pi {r}^{2} }{ \frac{198}{7} {r}^{2} } = \frac{22}{198} = \frac{1}{9} \times 100$

$= \frac{100}{9}percent \: or \: 11.1 \: percent$

Answer 2

Answer:

Hey mate here is your answer.....

Let d1 be the diameter and r is the radius of a circle.

d1 = 2.r………………………..(1)

If new radius is 3r. and diameter is d2 then:-

d2= 6r……………………………(2)

Dividing eqn. (2) by (1)

d2/d1= 6r/2r

d2/d1=3

or. d2= 3d1

Thus, the diameter of the circle is increased by 3 times. Answer

Step-by-step explanation:

Let radius be r then diameter be 2r

After increased by 3 times, new radius will be r+3r=4r

New diameter will be 2×4r= 8r=4×2r

Therefore diameter will increase by 4 times.

hope it's helpful for you...