Question

Two balls are drawn in succession without replacement from an urn containing four red balls and three black balls. Let X be the possible outcomes drawing red balls. Find the probability mass function and mean for X.

Answer 1

Number of Red balls = 4 

Number of Black balls = 3 

Total number of balls = 7 

Given: two balls are drawn in succession without replacement. 

Let ‘X’ be the number of red balls and ‘X’ can take the values 0, 1 and 2.