ardz24 wrote:A coin is tossed 7 times. Find the probability of getting more heads than tails in all 7 tosses?
A. 1/2
B. 63/128
C. 4/7
D. 61/256
E. 63/64
Ways to get MORE HEADS THAN TAILS:
4 heads, 3 tails
5 heads, 2 tails
6 heads, 1 tail
7 heads
Ways to get MORE TAILS THAN HEADS:
4 tails, 3 heads
5 tails, 2 heads
6 tails, 1 head
7 tails
Notice that the blue outcomes and the red outcomes are perfectly parallel.
Implication:
Since P(H) on any flip is the same as P(T) on any flip, the probability of getting the blue outcomes must be equal to the probability of getting the red outcomes.
Thus:
P(more heads than tails) = 1/2.
P(more tails than heads) = 1/2.
The correct answer is
A.
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