Data Sufficiency

The formula in the question makes this look complicated, but really we're just making an investment, and applying interest twice (with compounding). There's no need to even look at the formula.

If we know the exact size of the investment, and exactly how much interest we earn in two years, we can work out the interest rate, so Statement 1 is sufficient.

For Statement 2, we multiply the value of our investment by (1 + r/100) every time we want to add r% interest. So if we multiply by (1 + r/100)^2, we're adding r% interest twice. In words, Statement 2 just says "in two years, the investment earns more than 15% in interest". Certainly our interest rate could be very high, so the answer to the question could be yes - the annual interest rate might be larger than 8%.

We want to know if it's possible that the interest rate is less than 8%. You might think about what would happen with an annual interest rate exactly equal to 7.5% (exactly half of 15%). If we were applying simple interest, the value of the investment would increase by exactly 15% in two years. But if we compound, as we're doing here, we'll always earn more than if we don't compound. So at 7.5% annual interest, the investment in this question would earn more than 15% in two years. That means, if Statement 2 is true, our annual interest rate could also be 7.5%, and the answer to the question can be 'no'. So Statement 2 is not sufficient, and the answer is A.