HALF LIFE DECAY FORMULA

Solved Problems

Problem 1 :

The half-life of carbon-14 is approximately 6000 years. How much of 800 g of this substance will remain after 30,000 years?

Solution :

Half-Life Decay Formula :

A = P(1/2)^t/d

Substitute.

P = 800

t = 30000

d = 6000

Then,

A = 800(1/2)^30000/6000

= 800(1/2)⁵

= 800(0.5)⁵

= 800(0.03125)

= 25

So, 25 g of carbon-14 will remain after 30,000 years.

Problem 2 :

A certain radioactive substance has a half-life of 12 days. This means that every 12 days, half of the original amount of the substance decays. If there are 128 milligrams of the radioactive substance today, how many milligrams will be left after 48 days?

Solution :

Half-Life Decay Formula :

A = P(1/2)^t/d

Substitute.

P = 128

t = 48

d = 12

Then,

A = 128(1/2)^48/12

= 128(0.5)⁴

= 128(0.0625)

= 8

So, 8 milligrams of radio active substance will be left after 48 days.

Related Pages

Exponential Growth and Decay

Doubling-Time Growth Formula

Kindly mail your feedback to v4formath@gmail.com

We always appreciate your feedback.