Jane A. answered • 10/30/19

Experienced Ivy League Math tutor - Patient & Knowledgeable!

Half-life problems have the format of:

A(t) = A(0) (1/2) ^{t/t1/2 } where A(0) is the starting amount (or the amount when t = 0)

With the given information that A(0) is 100g (initial amount) and t_{½} is 10 years:

A(t) = 100 g (1/2) ^{t/10}

Thus:

A(0) = 100 g (1/2)^{0/10} = 100 g

A(20) = 100 g (1/2)^{20/10} = 25 g

A(60) = 100 g (1/2)^{60/10} = 1.5625 g

A(t) = 100 g (1/2) ^{t/10}

A(10) = 100 g (1/2) ^{10/10} = 50 g