Given that the measurement is in centimeters, find the circumference of the circle to the nearest tenth. (Use 3.14 for 71)
15.7 cm
31.4 cm
62.8 cm
78.5 cm

Suppose a laboratory has a 30 g sample of polonium-210. the half-life of polonium-210 is about 138 days how many half-lives of polonium-210 occur in 1104 days? how much polonium is in the sample 1104 days later? 9; 0.06 g 8; 0.12 g 8; 2,070 g