Hi boofhead,
The banks actually lend out each dollar to multiple people.
So in this case it would be 5% on 100k X 4 = $20k
Then from that they pay the interest to the lender (term deposit @ 6%), so $20k - $6k = $14k profit.
25,000 x 5% = $1250
25,000 x 5% = $1250
25,000 x 5% = $1250
25,000 x 5% = $1250
100000 X 5% = $5000