The ratio of the trains’ speeds is 3:2, so in a given length of time they’ll cover distances in that proportion. Thus they’ll meet 3/5 of the way from A to B. The faster train will reach that point in 3/5 of 8 hours, or at 11:48 a.m.

(Another approach: In each hour of travel the trains cover 1/8 and 1/12 of the distance AB, respectively, diminishing the distance between them by 1/8 + 1/12 = 5/24 of the total distance between A and B. Thus they’ll meet after 24/5 hours, or, again, 4 hours 48 minutes.)