Question 62329
Re: Width of a crater if cits circumference is 12.3 miles: 
12.3 (C) = 3.14d 
12.3 3.14d
---- = -----
3.14 3.14d 
= 3.9 width


This is already solved. I will try to explain what has happened in each step to maybe make it clearer.

The formula for cicumference  is
{{{Circumference = Pi * diameter}}} The width of the crater is another way of describing the diamter of a circle. In this problem we need to use the formula to find the diameter.

You know that the circumference of the crater is 12.3 miles. Your formula therefore becomes
{{{12.3 = Pi * diameter}}} divide both sides of the equation by Pi
{{{12.3 / Pi = Pi * diameter / Pi}}}
{{{12.3 / Pi = diameter}}} Use the value of Pi which you normally use (3.14 or the Pi button on the calculator etc).

Using posted problem as it is written shows that the answer would be 3.9 miles.