Strontinum-90 Has a Half Life of 29 $S = 100 e ^ { - 0.0238 t }$

Multiple Choice

Strontinum-90 has a half life of 29.1 years.The amount S of 100 kilograms of Strontinum6990 present after t years is given by $S = 100 e ^ { - 0.0238 t }$ How much of the 100 kilograms will remain after 50 years?

A) about 31.4 kilograms
B) about 35.4 kilograms
C) about 30.4 kilograms
D) about 37.4 kilograms
E) about 40.4 kilograms