The total number of outcomes when rolling two dice is $6 \times 6 = 36$The favorable outcomes for only one die showing 4 are:-Die 1 shows 4 and Die 2 shows anything but 4 (5 outcomes: 1, 2, 3, 5, 6).Die 2 Shows 4 and Die 1 shows anything but 4 (5 out comes: 1, 2, 3, 5, 6)Therefore, the total favorable outcomes = 5 + 5 = 10$\therefore \text{Probability} = \frac{\text{favorable outcomes}}{\text{Total outcomes}}$$= \frac{10}{36}$$= \frac{5}{18}$