Question 746653
Law of Total Probability:
P(2nd card = diamond) =
 P(2nd card = diamond|1st card = diamond)•P(1st card = diamond) + 
P(2nd card = diamond|1st card = NOT diamond)•P(1st card = NOT diamond)
= {{{(12/51)(13/52) + (13/51)(39/52)}}}
= {{{highlight(1/4)}}}