Question 1021428
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Hi  
15 batteries: 6E, 5D, 4P
'Chose' 2
P(the same brand) = [6C2 + 5C2 + 4C2]/15C2 = [ 15 + 10 + 6]/105 =  [31]/105= .2952 = 29.52%
note: 6C2 = 6!/2!4! = 6*5/2 = 15