54) Two persons each makes a single throw with  a pair of dice, The probability that the throws are unequal given by.
( a )   1 6 3 ( b )   73 6 3 ( c )   51 6 3 ( d )   n o n e   o f   t h e s e

Hi, 
P(scores unequal) = 1 - P(equal) = 1 - P(both total 2 or both total 3 or . . . or both total 12) 

P(both total 2) = P(1st totals 2)*P(2nd total 2) = (1/36)*(1/36) = 1/1296 

P(both total 3) = P(1st totals 3)*P(2nd totals 3) = (2/36)*(2/36) = 4/1296 

In a similar way the probability that both total 4, 5, 6, 7, 8, 9, 10, 11, 12 are 
9, 16, 25, 35, 25, 16, 9, 4, 1 each over 1296 

P(scores equal) = (1 + 4 + 9 + 16 + 25 + 36 + 25 + 16 + 9 + 4 + 1)/1296 
= 146/1296 = 73/648 

P(scores unequal) = 1 - 73/648 = 575/648
Regards

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