Bob invested $5,000 at a simple interest rate. in 15 years, the account was worth $6,500.what was the interest rate?

The interest rate is 2%. To solve, plug your variables into the simple interest rate formula, r = I/Pt, where r represents the rate, I represents interest, P represents your principal (starting) amount of money, and t represents time, and then simplify. (Subtract the final amount from the principal amount to get your interest, $1500.)

r = 1500/(5000*15)
r = 1500/75000 
r = .02 or 2% 

1. The principal has already selected a student from the voyagers, say Tom.

2.( Though it can ben Tom or the other 81 voyagers, it is often practical to make such assumptions, that is think "say the first selection was Tom from the voyagers"

3. Now the machine can again give the name of Tom. Now this is important, because we don't change the total number (the sample space) to 400-1=399. The sample space is still 400. 

4. P(voyager but not Tom)==