The question is written thusly:

Round 0.07284 to four, three, and two significant digits:

0.07284 (four significant digits)

0.0728 (three significant digits)

0.073 (two significant digits)

THe rules are:

1) All nonzero digits are significant.

2) All zeroes between significant digits are significant.

3) All zeroes which are both to the right of the decimal point and to the right of all non-zero significant digits are themselves significant.

Rule 3 states that the zero to the right of the decimal is Significant. Then would 4 significant digits be .0728?