Question

The half-life of a radioactive kind of tellurium is 30 hours. How much will be left after 90 hours, if you start with 468,960 grams of it?

Answer 1

Given:

The weight of tellurium is N(0)= 468960 grams.

The half-life time is T= 30 hours

The given time is t=90 hours

Recall the formula to find the weight of tellurium after t hours is

$N(t)=N(0)\times(0.5)^{(\frac{t}{T})}$

Substitute N(0)=468960, t=90 and T=30, we get

$N(90)=468960\times(0.5)^{(\frac{90}{30})}$

$N(90)=468960\times(0.5)^{(3)}$

$N(90)=58620$

Hence 58620 grams of the radioactive kind of tellurium will be left after 90 hours.