Neil buys 30 pens, 30 pencils, 30 rulers and 30 pencil cases.
2 answers:
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Answer:
The probability that there are more heads than tails is equal to .
Step-by-step explanation:
Since the number of flips is an odd number, there can't be an equal number of heads and tails. In other words, there are either
- more tails than heads, or,
- more heads than tails.
Let the event that there are more heads than tails be .
(i.e., not A) denotes that there are more tails than heads. Either one of these two cases must happen. As a result,
.
Additionally, since this coin is fair, the probability of getting a head is equal to the probability of getting a tail on each toss. That implies that (for example)
- the probability of getting 7 heads out of 15 tosses will be the same as
- the probability of getting 7 tails out of 15 tosses.
Due to this symmetry,
- the probability of getting more heads than tails (A is true) is equal to
- the probability of getting more tails than heads (A is not true.)
In other words .
Combining the two equations:
,
.
In other words, the probability that there are more heads than tails is equal to .
This conclusion can be verified using the cumulative probability function for binomial distributions with as the probability of success.
.