Strontium 90 is a radioactive waste product from nuclear reactors. it has a half-life of 29 years. how many years will it take for a quantity of strontium-90 to decay to 1/16 of its original mass?

116 years

Step-by-step explanation:

For this type of problems we have to use the formula that model the radioactive decay, that it's:

,

where correspond to the initial amount of mass of the element, correspond to the decay constant of the element, correspond the time measured in years and correspond to the amount of mass left after years.

In this case the original amount of mass is unknown but we don't need it to resolve the question, so let's make use of the half-life data that we've been given:

If the original amount of mass is then after = 29 years the amount of mass left is the half of .

, we cancel equal terms on both sides and obtain that , now we take natural logarithm on both sides (due to exponential function and logarithmic function are inverses) and then we obtain by dividing for -29, so

Now we know the formula that model the radioactive decay for Strontium-90:

So we've been asked for the time in years were the mass left will be the 1/16 of it's original mass,

By that time in years we have that , we cancel equal terms and take natural logorithm on both sides , finally we obtain after dividing that years

step-by-step explanation:

well if he bought them at 5 cedis each sold them at 7 cedis each then he would make a profit of 2 cedis of each book. if in total he made 150 cedis profit that means he sold 75 books. he lost 12 books at the start so that means he originally bought a total of 82 books.

step-by-step explanation: