So,
The probability of drawing a yellow marble is [tex] \frac{3}{7} [/tex].
Since he replaces the marble after it is drawn out, the probability of drawing another yellow is the same: [tex] \frac{3}{7} [/tex].
The probability of drawing a red marble is [tex] \frac{4}{7}[/tex].
In order to get the probability of drawing 2 yellow marbles and 1 red marble, given that each marble is replaced after it is drawn out, we must multiply the fractions together.
[tex]( \frac{3}{7} )( \frac{3}{7} )( \frac{4}{7} ) = \frac{36}{343} [/tex]
Because the order of the marbles doesn't matter, we will multiply the probability by 3.
[tex]3( \frac{36}{343} ) = \frac{108}{343} [/tex]
