the moon is 2.39x10^5 miles from the earth. the average man is 6ft tall. How many men would have to stand on top of one another to reach from earth to the moon

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