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If a fair coin is tossed 5 times, what is the probability, to the nearest thousandth, of getting exactly 4 tails?
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If a fair coin is tossed 55 times, what is the probability, to the nearest thousandth, of getting exactly 44 tails?\newlineAnswer:

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Q. If a fair coin is tossed 55 times, what is the probability, to the nearest thousandth, of getting exactly 44 tails?\newlineAnswer:
  1. Determine probability of tail: Determine the probability of getting a tail on a single coin toss.\newlineA fair coin has two sides, heads and tails, so the probability of getting a tail on a single toss is 12\frac{1}{2}.
  2. Calculate 44 tails in 55 tosses: Calculate the probability of getting exactly 44 tails in 55 tosses.\newlineThis is a binomial probability problem, where we want exactly 44 successes (tails) in 55 trials (tosses), with the probability of success on each trial being 12\frac{1}{2}.\newlineThe binomial probability formula is:\newlineP(X=k)=(nk)(pk)((1p)(nk))P(X = k) = \binom{n}{k} \cdot (p^k) \cdot ((1-p)^{(n-k)})\newlinewhere:\newline- P(X=k)P(X = k) is the probability of getting kk successes in nn trials,\newline- (nk)\binom{n}{k} is the number of combinations of nn things taken kk at a time,\newline- 5522 is the probability of success on a single trial,\newline- 5533 is the probability of failure on a single trial.
  3. Calculate combinations of 55 things: Calculate the number of combinations of 55 things taken 44 at a time.\newline((54)=5!4!×(54)!=51=5)(5 \choose 4) = \frac{5!}{4! \times (5-4)!} = \frac{5}{1} = 5
  4. Use binomial probability formula: Calculate the probability using the binomial probability formula.\newlineP(X=4)=(54)(12)4(12)54P(X = 4) = \binom{5}{4} \cdot \left(\frac{1}{2}\right)^4 \cdot \left(\frac{1}{2}\right)^{5-4}\newlineP(X=4)=5(12)4(12)1P(X = 4) = 5 \cdot \left(\frac{1}{2}\right)^4 \cdot \left(\frac{1}{2}\right)^1\newlineP(X=4)=511612P(X = 4) = 5 \cdot \frac{1}{16} \cdot \frac{1}{2}\newlineP(X=4)=532P(X = 4) = \frac{5}{32}
  5. Convert probability to decimal: Convert the probability to a decimal to the nearest thousandth. \newlineP(X=4)=5320.15625P(X = 4) = \frac{5}{32} \approx 0.15625\newlineTo the nearest thousandth, this is approximately 0.1560.156.

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