7. debra arthur earns a weekly salary of $472 at all sports. next month she will
be promoted from assistant buyer to head buyer. in her new position she will
be paid $1,200 semimonthly. how much more per year will she earn as head
buyer than as assistant buyer?

chad should not have included the values (1, 2) and (3, 6) because that would mean he only had half a healing card.

146

step-by-step explanation:

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

source:  

the answer is  

d.

21

i did this one. so you should get it right.