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if 9 coins are tossed N (N a given number), construct the corresponding histogra

ID: 3135372 • Letter: I

Question

if 9 coins are tossed N (N a given number), construct the corresponding histogram for the theoretical frequency of 0,1,2,...,9 heads given below. in this case N=512. note that the fractions in the second columns are left unreduced on purpose.
x.           f.                    expected(binomial)f
0.           (1/512)N
1.            (9/512)N
2.             (36/512)N
3.           (84/512)N
4.          (126/512)N
5.           (126/512)N
6.           (84/512)N
7.            (36/512)N
8.             (9/512)N
9.             (1/512)N

noting that the histogram is symmetric, calculate the mean and the standard deviation.

Explanation / Answer

If 9 coins are tossed N (N a given number), construct the corresponding histogram for the theoretical frequency of 0, 1, 2,..., 9 heads given below. In this case N=512. Note that the fractions in the second columns are left unreduced on purpose.

Noting that the histogram is symmetric, calculate the mean and the standard deviation.

Solution:

The table for the calculations purpose is given as below:

x

f

p

XP(x)

x - mean

(x - mean)^2

(x - mean)^2 * P(x)

0

1

0.001953125

0

-4.5

20.25

0.039550781

1

9

0.017578125

0.017578125

-3.5

12.25

0.215332031

2

36

0.0703125

0.140625

-2.5

6.25

0.439453125

3

84

0.1640625

0.4921875

-1.5

2.25

0.369140625

4

126

0.24609375

0.984375

-0.5

0.25

0.061523438

5

126

0.24609375

1.23046875

0.5

0.25

0.061523438

6

84

0.1640625

0.984375

1.5

2.25

0.369140625

7

36

0.0703125

0.4921875

2.5

6.25

0.439453125

8

9

0.017578125

0.140625

3.5

12.25

0.215332031

9

1

0.001953125

0.017578125

4.5

20.25

0.039550781

512

1

4.5

0

82.5

2.25

Mean = XP(X) = 4.5

Variance = (x - mean)^2 * P(x) = 2.25

Standard deviation = sqrt (2.25) = 1.5

x

f

p

XP(x)

x - mean

(x - mean)^2

(x - mean)^2 * P(x)

0

1

0.001953125

0

-4.5

20.25

0.039550781

1

9

0.017578125

0.017578125

-3.5

12.25

0.215332031

2

36

0.0703125

0.140625

-2.5

6.25

0.439453125

3

84

0.1640625

0.4921875

-1.5

2.25

0.369140625

4

126

0.24609375

0.984375

-0.5

0.25

0.061523438

5

126

0.24609375

1.23046875

0.5

0.25

0.061523438

6

84

0.1640625

0.984375

1.5

2.25

0.369140625

7

36

0.0703125

0.4921875

2.5

6.25

0.439453125

8

9

0.017578125

0.140625

3.5

12.25

0.215332031

9

1

0.001953125

0.017578125

4.5

20.25

0.039550781

512

1

4.5

0

82.5

2.25