Asample of phosphorus-32 has a half-life of 14.28 days. if 55 g of this radioisotope remain (1 point) unchanged after approximately 57 days, what was the mass of the original sample? 

For this problem, we use the formula for radioactive decay which is expressed as follows:

An = Aoe^-kt

where An is the amount left after time t, Ao is the initial amount and k is a constant. 

We calculate as follows:

An = Aoe^-kt
0.5 = e^-k(14.28)
k = 0.05

An = Aoe^-kt
An = 55e^-0.55(57)
An = 1.33x10^-12 g

Arise 8 run 1 this means go 8 up and 1 across, which is steepest