13. A variety of pea plants producing yellow (y) owers with round (r) pollens are crossed with plants that produce green (g) owers with wrinkled (w) pollens. According to Mendelian theory of heredity, 9/16 of the osprings produce yr owers, 3/16 produce yw owers, 3/16 produce gr owers and the remaining 1/16 produce gw owers. A random sample of 20 osprings is selected. (a) What is the probability that 12 of them produce yr owers? (b) What is the probability that 4 of them produce yw owers, 3 produce gr owers and 1 produces gw owers? (c) If 12 of them produce yr owers what is the probability that in the remaining 8 plants 4 produce yw owers, and 3 produce gr owers?