Let P(t) Be the Quantity of Strontium-90 Remaining After T $\frac { 1 } { 2 }$

Multiple Choice

Let P(t) be the quantity of strontium-90 remaining after t years. Suppose the half-life of strontium-90 is 28 years. Which of the following equations expresses the half-life information?

A) P(28) = $\frac { 1 } { 2 }$ $\mathrm { P } _ { 0 }$
B) P $\frac { 1 } { 2 }$ = 28 $\mathrm { P } _ { 0 }$
C) 28 = $\frac { 1 } { 2 }$ $\mathrm { P } _ { 0 }$
D) 28 = $\frac { 1 } { 2 }$ $\mathrm { P } _ { 0 }$ $\mathrm { e } ^ { - \mathrm { kt } }$
E) none of these