Two positions of a dice with 1 to 6 dots on its sides are shown below. If the dice is resting on the side with three dots, what will be number of dots on the side at the top?

From figures (i) and (ii) we conclude that 2, 6 and 4 dots appear adjacent to 3 dots. Hence, either 1 or 5 dots may appear opposite 3 dots. Thus, if the dice is resting on the side with three dots, then the number of dots on the side at the top is either 1 or 5.