Suppose \( a_{1}, a_{2}, 2, a_{3}, a_{4} \) be in an arithmetico-geometric progression. If the common ratio of the corresponding geometric progression is \( 2 \) and the sum of all \( 5 \) terms of the arithmetico-geometric progression is \( {49}/{2} \), then \( a_{4} \) is equal to ______.
