# The half-life of chromium-51 is 28 days. If you start with 640 g, how much will be left after 56 days?

Jun 8, 2018

The mass left after $56 \text{ days }$ is $= 160 g$

#### Explanation:

The half life of Chromium - $51$ is ${t}_{\frac{1}{2}} = 28 d$

The original mass is ${m}_{0} = 640 g$

Then , after $28$ days, the mass will be ${m}_{28} = {m}_{0} / 2 = \frac{640}{2} = 320 \text{ g}$

and after $56$ days, the mass will be ${m}_{56} = {m}_{0} / 4 = \frac{640}{4} = 160 \text{g }$

Therefore,

The mass left after $56 \text{ days }$ is $= 160 g$