word problems (compound interest related)

Hi guys,

Can any one help me with some of these problems? Doing em for extra credit for high school thanks. These are interest (simple and compound) related, btw.

1) how long would it take to double your money in an account paying 6% compounded quarterly? After what time period would the interest earn equal the original princiaapl in an accout payin 6 % everyday?

2) a house is bought for $330,000 with a down payment of $40,000. what is the semi-annual payment for 25yrs if the interst rate is 12% comppunded semi-annually?

thanks! =)