How Old at $4,000?Date: 10/15/2002 at 17:48:57 From: Stephen Subject: Word Problem Aunt Isabella sends money to each niece and nephew on his or her birthday. She gives each child $10.00 on his or her first birthday.On each birthday thereafter, you and your cousins get $20.00 more than on the birthday before. How old will you be when you receive a total of $4,000.00 from Aunt Isabella? Date: 10/15/2002 at 20:12:33 From: Doctor Ian Subject: Re: Word Problem Hi Stephen, Instead of thinking about dollars, let's think about $10 bills. She gives you 1 of them on your first birthday, 3 the next one, 5 the next one, and so on. Suppose you save them, and use a magic marker to mark each one with the number of the birthday when you got it. Then you lay them out on a table like this: [1] [2] [3] [4] [2] [2] [3] [4] [3] [3] [3] [4] [4] [4] [4] [4] Do you see how each birthday adds one more 'layer' to the square? How big would the square have to get for you to have 400 ten-dollar bills (which is the same as $4000)? How many years would it take to get that big? - Doctor Ian, The Math Forum http://mathforum.org/dr.math/ |
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