Assuming that the balls are not replaced;
[tex] \frac{6}{9}* \frac{5}{8}* \frac{4}{7}* \frac{3}{6} [/tex]= 5/42
(the numbers are decreasing in the denominator as you are presumably taking out the red balls. In the denominator, there is one less ball each time since you took out a red one).
Therefore, the probability of selected 4 red balls consecutively without replacement is 5/42.
Hope I Helped :)
