Concept:The probability of selecting a white ball changes after each draw because two additional balls of the same colour are added.
Explanation:• Initially, white = 3, red = 5, total = 8.
•
P(white on 1st)=83​.
• After drawing a white, it is replaced and 2 more whites are added. So white becomes
3+2=5, red remains 5, total = 10.
•
P(white on 2nd∣white on 1st)=105​=21​.
• After second white, white becomes
5+2=7, red remains 5, total = 12.
•
P(white on 3rd∣white on 1st and 2nd)=127​.
• Required probability =
83​×21​×127​=19221​=647​.
Answer:647​ (Option A).