SOLUTION: If 10g of a radioactive substance are present initially and 9yr later only 5 remain, how much of the substance will be present after 18 yr?

Question 1158289: If 10g of a radioactive substance are present initially and 9yr later only 5 remain, how much of the substance will be present after 18 yr?
Answer by ikleyn(52909) (Show Source): You can put this solution on YOUR website!
.


From the condition, the half-life period is 9 years.


Hence, after 18 years since the starting moment, the remaining amount will be half of 5 grams, i.e. 2.5 grams.   ANSWER

Solved.

RELATED QUESTIONS
If 10g of a radioactive substance are present initially and 3 years later only 5g remain, (answered by CubeyThePenguin)

If 800g of a radioactive substance are present initially and 8 years later only 450g... (answered by greenestamps,ikleyn)

If 10 g of a radioactive substance are present initially and 9 yr later only 5 g... (answered by josgarithmetic)

If 18g of a radioactive substance are present initially and 5 yr later only 9 g remain,... (answered by josgarithmetic)

Please help me with this word problem, I'm out of my depth: If 12 g of a radioactive... (answered by josgarithmetic)

My problem is with entering e raised to a negative power on my TI-84 Plus calculator. I... (answered by Edwin McCravy)

A radioactive substance has a halflife of 120 years. If 200mg of substance was present,... (answered by ewatrrr)

A radioactive substance has a halflife of 120 years. If 200mg of substance was present,... (answered by josgarithmetic)

Suppose that a certain radioactive substance has a half-life of 20 years. If there are... (answered by ankor@dixie-net.com)