a box contains ten marbles,seven of which are black and three are red.three marbles are drawn one after the other without replacement,find the probability of choosing at most two black marbles

Question

at most two black marbles

Answer 1

A box contains ten marbles, seven of which are black and three are red.three marbles are drawn one after the other without replacement. Find the probability of choosing
A. At least two black marbles
P(X ≥ 2) = 1 - P(X = 0) - P(X = 1)
= 1 -  - 

=  or  (4 decimal places) 
B. At most two black marbles
P(X ≤ 2) = P(X = 0) + P(X = 1) + P(X = 2)
=  +  +  
=  or  (4 decimal places)