The circumference of a roll of party streamers is 9 inches. The circumference decreases by 2 inches after you use the streamers to decorate for a graduation party. Find the diameter of the roll after the decrease. Round your answer to the nearest hundredth.

For that case the new circumference is:

C = 9 - 2

C = 7 inches

By definition, the circumference is:

C = 2 * pi * r

Where,

r: radio

Substituting values:

7 = 2 * pi * r

Clearing the radio:

r = 7 / (2 * pi)

Then, the diameter is:

d = 2 * r

Substituting:

d = 2 * (7 / (2 * pi))

d = 2.228169203

Round to the hundredth:

d = 2.23 inches

Answer:

The diameter of the roll after the decrease is:

d = 2.23 inches