How do you do this pi math problem?

Question

Here's the question. I don't get it. I would like explanations please

A signal from a walkie-talkie can be received up to one mile away. A signal from a CB radio can be received up to 5 miles away. Note the 5 mile signal and one mile signal are the radiuses of a circle. The diagram shows a small circle drawn inside a large circle. the large circle represents the CB radio, while the small circle represents the walkie talkie.

Part a/ Over how great an area can a walkie talkie transmit a signal? Express your answers in terms of pi.

Part b/ Over how great an area can a CB radio transmit a signal. Express you answer in terms of pi.

Part c/ write a ratio to compare the area of CB radio reception to the area of walkie talkie reception.

Answer 1

The area of a circle with radius r is given by A = πr^2.

a) Radius is 1 mile, area is π(1)^2 = π square miles.
b) Radius is 5 miles, area is π(5)^2 = 25π square miles.
c) The ratio is (25π) / (π) = 25.

Answer 2

Whoever gave you this problem doesn't know the plural of "radius", but I digress.

A) The area of a circle is π r ², where "r" is the circle's radius. So if the walkie-talkie coverage area has a radius of 1 mile, then the area it covers is π(1)² = π square miles.

B) The CB coverage area has a radius of 5 miles, so the area it covers is π(5)² = 25π square miles.

C) The ratio of the CB's reception area to that of the walkie-talkie is 25π / π = 25:1.

Answer 3

The area of a circle is expressed mathematically as pi *r^2 (pi times radius squared). Therefore a) Radius is 1 mile, so pi*r^2 = pi *1 or pi square miles. Use the same procedure for b), and compare a) and b) to get c).

Answer 4

Part A) Area = Pi X (RXR)
Area = 3.14 X (1 mile X 1 mile)
Area = 3.14 X (1 mile Sqaured)
Area = 3.14 Sqaure miles

Part B) Area = Pi X (RXR)
Area = 3.14 X (5 mile X 5 mile)
Area = 3.14 X (25 miles Sqaured)
Area = 78.5 sqaure miles

Part C) Ratio of Part B to Part A
Ratio = 78.5 to 3.14
Ratio = 78.5 divided by 3.14 to 3.14 divided by 3.14
Ratio = 25 to 3.14 divided by 3.14
Ratio = 25 to 1