Assuming they are dice, to work out the probability that the product is 8, the dice either have to be 2 and 4 or 4 and 2. The blue dice therefore has to be a 2 (4 is not less than 3), which is a 1 in 6 probability. The yellow one therefore has to be 4, which again is 1 in 6. The probablility that these both happen at the same time is given when they are multiplied together. [tex] \frac{1}{6} [/tex]x[tex] \frac{1}{6} [/tex] = [tex] \frac{1}{36} [/tex].
Hope that is useful.