1 - The rule of 72 is you divide the interest rate into 72 and you'll find out how many years it will take for your money to double. Do it as many times as necessary from age 16 to 52.

For example, @ 6% divided into 72 is 12 so the 300 will be $600 in 12 years. Kind of simple if the 6% is never going to change. Now you know what the Rule of 72 is so you can figure it out.

#2 - I don't understand this question.

it will double at age 28[1],again at age 40[2] and at age 52 [3]-$600 at 28,$1,200 at 40 and $2,400 at age52. this could be a trick question since a money market account pays a different rate of interest every year-their is no way you could use the rule of 72 for a money market account

#1: mark has invested $300 it age 16 into a money marcket account earning 6%. How many times will mark's investment double before age 52 what will his investment be worth ? What would mark's investment be if he had investment at age 28? .... i think there are 3 questions on #1.......................... #2: jackies's parents invested $3000 in to a common stock earning 10% when she was born. How many times will jackie's parents had waited to invest útil she was age 7? ............ if someone can help me pleasee???