An investor owns three common stocks Each stock independent of the others?

Probability that stock A will increase in value = 1/3

Probability that stock A will not increase = 2/3

If stock A does not increase, Stock B and C must increase.

2/3 * 1/3 * 1/3 = 2/27

Similar for Stock B ( A and C must increase) or for C (A and B must increase)

2/27 * 3 = 6/27

One additional possibility exists where A, B, and C all increase

1/3 * 1/3 * 1/3 = 1/27

6/27 + 1/27 = 7/27 = 0.259 <====