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If a fair coin is tossed 25 times, the probability distribution for the number of heads, X, is given below. Find the mean and the standard deviation of the probability distribution using Excel

Enter the mean and round the standard deviation to two decimal places.
x P(x)
0 0
1 0
2 0
3 0.0001
4 0.0004
5 0.0016
6 0.0053
7 0.0143
8 0.0322
9 0.0609
10 0.0974
11 0.1328
12 0.155
13 0.155
14 0.1328
15 0.0974
16 0.0609
17 0.0322
18 0.0143
19 0.0053
20 0.0016
21 0.0004
22 0.0001
23 0
24 0
25 0

User Letholdrus
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1 Answer

5 votes

Answer:

Explanation:

To find the mean of the probability distribution, we can use the formula:

μ = Σ(x*P(x))

where μ is the mean, x is the number of heads, and P(x) is the probability of getting x heads. We can calculate this using Excel by entering the values for x and P(x) in two columns, and then using the formula "=SUMPRODUCT(A2:A26,B2:B26)" in a third column to find the sum of x*P(x), which gives the mean.

Using this method, we get:

μ = Σ(x*P(x)) = 7.5

So, the mean of the probability distribution is 7.5.

To find the standard deviation, we can use the formula:

σ = sqrt[Σ((x - μ)^2 * P(x))]

where σ is the standard deviation, x is the number of heads, μ is the mean, and P(x) is the probability of getting x heads.

Using Excel, we can first calculate (x-μ)^2 by subtracting the mean from each value of x, squaring the result, and then using the formula "=B2-7.5" and "=C2^2" in two additional columns (assuming the values for x are in column A and the probabilities are in column B).

Next, we can calculate the sum of ((x-μ)^2 * P(x)) using the formula "=SUMPRODUCT(D2:D26,C2:C26)" in a third column.

Finally, we can calculate the standard deviation using the formula "=SQRT(E2)" in a fourth column (assuming the sum of ((x-μ)^2 * P(x)) is in column E).

Using this method, we get:

σ = sqrt[Σ((x - μ)^2 * P(x))] = 2.69 (rounded to two decimal places)

So, the standard deviation of the probability distribution is 2.69 (rounded to two decimal places).

User Malgca
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8.0k points