2 and half
A radio station's signal has a radius of 100 miles. If you drive at a constant speed of 40 miles an hour, non stop, directly across the diameter of the signal; how long can you listen to the station before the signal fades?
It's quite easy to work out how long you can listen to a radio station before the signal fades if you're travelling at 40 miles an hour across the diameter of the 100-mile radius signal. The best thing to do is break it down!
Firstly, let's be clear on what radius and diameter mean.
- Radius - the distance of a circle from the middle to the outside.
- Diameter - the distance across the whole of the circle. It is double the radius.
- The radius of the signal is 100 miles, and since the diameter is double the radius, you'll be driving 200 miles.
- You're travelling at 40 miles an hour, so to work this out you can do a simple division sum: 200/40=5. Alternatively, you could count how many 40's go into 200... The answer is 5!
- So there you have it. You can drive for 5 hours at 40 miles an hour listening to the radio before the signal fades. Hope this helps!
It looks like someone has already asked this question. Take a look at this version to find out some different ways of working the problem out: http://entertainment.blurtit.com/3105468/a-radio-stations-signal-has-a-radius-of-100-miles-if-you-drive-at-a-constant-speed-of-40
This video is kinda cool, you can learn about the maths behind circles through music! Take a look below: