One way that researchers study the effects of trans fats on people's health is by setting up controlled experiments. for example, in an experimental feeding trial, participants agree to stick to specific diets that the researchers prescribe. in this case, the researchers might vary the proportions of saturated, unsaturated, and trans fats in the diet of each participant. throughout the study, the health status of the participants is monitored closely. suppose that you are a researcher designing an experimental feeding trial. how would you set up your study and what limitations would you face?

Simon, aged 10, is invited to a classmate's birthday party at an exclusive ski resort on march 15th. the day will include 4 hours of snowboarding, lunch and birthday cake. simon's mother checks a box on the invitation that says "yes, we will attend" and returns it to the classmate's address. unfortunately, they later don't attend the party when simon comes down with the flu. on march 17th, simon's mother receives an invoice in the mail from simon's classmate for $35 that says, "party no-show fee." can simon's classmate collect the fee?

Suppose you win a small lottery and have the choice of two ways to be paid: you can accept the money in a lump sum or in a series of payments over time. if you pick the lump sum, you get $2,950 today. if you pick payments over time, you get three payments: $1,000 today, $1,000 1 year from today, and $1,000 2 years from today. 1) at an interest rate of 6% per year, the winner would be better off accepting the (lump sum / payments over time), since it has the greater present value. 2) at an interest rate of 9% per year, the winner would be better off accepting the (lump sum / payments over time), since it has the greater present value. 3) years after you win the lottery, a friend in another country calls to ask your advice. by wild coincidence, she has just won another lottery with the same payout schemes. she must make a quick decision about whether to collect her money under the lump sum or the payments over time. what is the best advice to give your friend? a) the lump sum is always better. b) the payments over time are always better. c) it will depend on the interest rate; advise her to get a calculator. d) none of these answers is good advice.

Your subscription to investing wisely weekly is about to expire. you plan to subscribe to the magazine for the rest of your life, and you can renew it by paying $85 annually, beginning immediately, or you can get a lifetime subscription for $620, also payable immediately. assuming that you can earn 6.0% on your funds and that the annual renewal rate will remain constant, how many years must you live to make the lifetime subscription the better buy?