A scientist has 20 grams of the radioactive isotope sodium-24. The isotope decays exponentially as shown in the table.
Time (hours)
Mass (grams)
un
15.9
10
12.6
15
10
20
7.9
25
6.3
30
5
Approximately what will the mass of the isotope be after 45 hours? A
A 1.5 grams
B. 2.5 grams
C. 3.5 grams
D
4.5 grams

Suppose you just purchased a digital music player and have put 8 tracks on it. after listening to them you decide that you like 4 of the songs. with the random feature on your player, each of the 8 songs is played once in random order. find the probability that among the first two songs played (a) you like both of them. would this be unusual? (b) you like neither of them. (c) you like exactly one of them. (d) redo () if a song can be replayed before all 8 songs are played.

Simplify using positive exponents only.

Tim earns $120 plus $30 for each lawn he mows.write an iniqualityvto represent how many lawns he needs to mow to make more than $310