Question

The circumference of a circle varies directly with its radius. if the circumference of a circle with a radius of 1.5 inches is 9.42 in, what is the circumference of a circle with a radius of 9 in? use π = 3.14. round your answer to the nearest inch.

Answer 1

1) Circumference = 2πr
C = 2 x π x 9
C = 18π = 56.548... = 57 inches (to the nearest inch)

2) 6h = $52.50
1h = $52.50/6 = 8.75
11h = 8.75 x 11 = $96.25 = $96 (to the nearest cent)

Answer 2

Answer: 57 in.

Explanation:

When two quantities x and y are directly proportional , then the equation to show direct proportion is given y :-

`(x_1)/(y_1)=(x_2)/(y_2)` (1)

Given : The circumference of a circle varies directly with its radius.

Let c be the circumference of a circle with a radius of 9 in.

If the circumference of a circle with a radius of 1.5 inches is 9.42 in, then from (1) we have

`(c)/(9)=(9.42)/(1.5)\\\\\Rightarrow\ c=(9.42)/(1.5)*9=56.52\approx57\ in.`

Hence, the circumference of a circle with a radius of 9 in is approximately 57 in.