Answer: B. 143/400
Explanation:
To find the missing probability P(A∩B), we can use the formula: 
 P(A∩B) = P(A) * P(B|A) 
Given: P(A) = 11/20 P(B|A) = 13/20 
Substituting the values into the formula:
 P(A∩B) = (11/20) * (13/20) 
Multiplying the fractions:
 P(A∩B) = 143/400 
Therefore, the missing probability P(A∩B) is 143/400. 
The correct answer is B. 143/400.