Calculating compounding interest?

Question

Can someone help me understand how to calculate compounding interest in a problem like the one below?

Joe deposits $100 in an account paying 5% interest compounded annually. His parents open a non-interest bearing account in which they deposit $25 a year on his birthday. How many years will pass before the accounts contain the same amount of money?

Answer 1

I like to make a charge for these problems. It's easy to visualize that way.

at the end of:

                     Joe's account               |     Parents account

Year 1         $100*1.05 = $105        |     $25

Year 2         $105*1.05 = $110.25   |    $50

Year 3         $115.76                          |    $75

Year 4         $121.55                          |    $100

year 5         $127.62                           |    $125

The amounts will cross in the 5th year.

Answer 2

hi,

amount by compound intrest:=p(1+r/100)

p=principle

r=rate

it will be same after 5 years.

Answer 3

yuno it gotta be > 4 yeers kauz 25$/yeer add up tu 100$ after 4 yeers

???? maebee at yeer 5 ??? parents hav 125$ then

not kleer, kauz yu dont sae WEN parents put up the 25$...

maebee at same start time him put up 100$ ????????????

but mite be at END av yeer 1