posted by Sam .
Suppose that the allele for tallness (T) is dominant over shortness (t); that for Yellow (Y) is dominant over green (y); and that for roundness (W) is dominant over wrinkled (w). Suppose we cross two plants with genotypes TTYyWw and TtYyWw. The probability of a Tall, Yellow, Round plant is:
Using a Punnett square, all will be Tall with at least one T, 3/4 will be Yellow (with at least one Y gene) and 3/4 will be Round (with at least one W gene).
The probability of all events occurring is found by multiplying the probability of the individual events.
I assume you can do the multiplication.