In this problem, we know that Harry saved $100 each week for 8 weeks. In other words, he saved a total amount of money:
[tex]\text{Amount of money saved}=8\times 100=\$800[/tex]
We know that he earned $48 on his savings of $800, so for every $100 the interest (I) he earns is:
[tex]I=\frac{48}{8}=\$6[/tex]
So, in conclusion Harry did earn $6 in interest for every $100