Answer
See below.
Work Step by Step
In this case the probability of guessing correctly will be $\frac{1}{4}$ and of guessing incorrectly will be $\frac{3}{4}$.
By definition, the expected value is the sum of each outcome multiplied by its probability. Hence here the expected value: $\frac{1}{4}\cdot1+\frac{3}{4}\cdot(-\frac{1}{4})=\frac{1}{16}$, which is positive, thus it is worth guessing.
