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If you flip a coin 13 times, what is the probability of getting 7 or fewer heads?

a) 0.017
b) 0.318
c) 0.682
d) 0.983

1 Answer

5 votes

Final answer:

The probability of getting 7 or fewer heads when flipping a coin 13 times is approximately 0.682.

Step-by-step explanation:

To find the probability of getting 7 or fewer heads when flipping a coin 13 times, we need to calculate the probability of getting 0, 1, 2, 3, 4, 5, 6, or 7 heads. Each flip of a fair coin has a 50% chance of landing heads or tails, so the probability of getting a specific number of heads is calculated using the binomial probability formula.

The probability of getting exactly k heads in n flips is given by the formula:

P(X=k) = C(n, k) * p^k * (1-p)^(n-k)

Where C(n, k) is the number of combinations of n items taken k at a time, p is the probability of getting a head (0.5 for a fair coin), and n is the number of flips.

For the given problem, the probability of getting 7 or fewer heads in 13 flips can be calculated as:

P(X≤7) = P(X=0) + P(X=1) + P(X=2) + P(X=3) + P(X=4) + P(X=5) + P(X=6) + P(X=7)

By plugging in the values into the formula and calculating the probabilities for each number of heads, we find that the probability of getting 7 or fewer heads is approximately 0.682.

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