Assessment Brief

1. Suppose strontium-90 decays at a rate of 2 percent per year.(a) Write the fraction P of strontium remaining, as function of t, measured in years. (Assume that at time t=0 there is 100 % remaining.) Answer: P(t)=(b) Estimate the half-life of strontium. Answer:  (c) If presently there is 4 grams of strontium, estimate how many grams of the substance will remain after 50 years. 2. Your business associate who owes you $9000 offers to pay you either $7110 now or else to pay you 6 yearly installments of $1500, the first installment paid now. Assume a 6.2% market interest rate, compounded continuously. How much would you have at the end of 6 years if you choose to take the $ 7110 offer now, and you use the market to earn interest on the funds? $ How much would you have at the end of 6 years if you choose to take the installments each year, and you still used the market to earn interest on the the funds? $ Is it better to take the lump sum? (Y for yes, N for no.)