Answer:
V ≈ 21941.33 yd.
Step-by-step explanation:
I just calculated each side with the help of my trusty calculator! Hope this helped! Comment if you are still confused!
<span>You would have to wait 318 years for 1/5 (20%) of the Radium to disappear. 1590 is the point where half of the Radium would decay, so if you take 20% of that, it would equate out to 318 years. Radium has a long half life!</span>