The correct answer is:
The estimate is between 8 and 9.
Step-by-step explanation:
Perfect squares are numbers whose square roots are whole numbers. 78 is not one; however, it is between two others, namely 64 and 81.
64 is the perfect square of 8, since 8(8) = 64.
81 is the perfect square of 9, since 9(9) = 81.
78 is between these two; since it is closer to 81, this means the answer will be a decimal between 8 and 9, but that is closer to 9.