In this paper we provide a $4$-GDD of type $2^2 5^5$, thereby solving the existence question for last remaining feasible with no more than $30$ points. We then show that $4$-GDDs $2^t 5^s$ exist all but finite specified set pairs $(t,s)$.

A group divisible design is resolvable if there exists a partition n = {P,, Pz, . .} of p such that each part Pi is itself a partition of X. In this paper we investigate the existence of resolvable group divisible designs with K = {3}, M a singleton set, and all A. The case where M = { 1) has been solved by Ray-Chaudhuri and Wilson for I = 1, and by Hanani for all h > 1. The case where M is a s...