Circumference is found with the formula
c = pi × d
d is diameter and we will use 3.14 for pi.
The diameter is the measure across the center of the circle. In the first problem, you are given the radius, so we have to multiply by 2 to get the diameter. Then we can use the formula.
12.4 in × 2 = 24.8 in (that's the diameter)
c = pi × D
c = 3.14 × 24.8
c = 77.872 inches
circumference is 77.872 inches.
Try the other problems on your own. They are just like this one. Just make sure they are giving you the diameter and not the radius. Post if you have problems.
Answer:
(write them out and convert them all into mixed fractions)
(find the LCD aka least common denominator)
(add all numerators together)
(this is improper, so you need to convert back to mixed by dividing)
(this is your answer)
The answer is 36.
Because 20% of 36 is equal to 7.2
And 36 - 7.2 = 28.80
