They say in the main stem that the two investments earned the same amount of simple annual interest, the phrase “simple annual interest” refers to the amount of simple interest that one would earn over a period of one year and that is why the duration is fixed for one year.

Naina says

How can we assume that time period is same for both investments in statement 1?

GMAT Quantum says

Hi Naina,

They say in the main stem that the two investments earned the same amount of simple annual interest, the phrase “simple annual interest” refers to the amount of simple interest that one would earn over a period of one year and that is why the duration is fixed for one year.

I hope this makes sense.