In: Statistics and Probability
Answer)
Probability is = (favorable)/(total)
Total = 52
A)
Favorable = seven or eight or ten
There are 4 sevens and 4 eights and 4 tens in a standard deck of a card
Required favorable here is 4+4+4 = 12
Required probability is = 12/52 = 0.2307692307692
B)
Favorable = heart or club or spade
There are 13 hearts and 13 clubs and 13 spades
Favorable = 13+13+13 = 39
Required probability = 39/52
= 0.75
C)
Favorable = five or ace or heart
There are 4 fives and 4 ace and 13 hearts
But we need to subtract 2 from the sum, to eliminate the double counting of heart ace and 5 of heart.
= 4+4+13-2
= 19
Required probability = 19/52 = 0.3653846153846
D)
Favorable = queen or eight or club or spade
There are 4 queens and 4 eights and 13 clubs and 13 spades.
But we need to subtract 4 from the sum to eliminate double counting
Favorable = 4 + 4 + 13 + 13 - 4 = 30
Required probability = 30/52 = 0.5769230769230