There are 6 blue marbles, 4 yellow marbles, and 10 total marbles for the first pick, so the probability of picking a blue marble is [ggfrac]6/10[/ggfrac], or [ggfrac]3/5[/ggfrac]. For the second pick, there are 5 blue marbles, 4 yellow marbles, and 9 total marbles, so the probability of picking a yellow marble for the second pick is [ggfrac]4/9[/ggfrac]. The probability of picking a blue marble on the first pick and a yellow marble on the second pick is [ggfrac]3/5[/ggfrac] × [ggfrac]4/9[/ggfrac] = [ggfrac]12/45[/ggfrac], or [ggfrac]4/15[/ggfrac].