3 years ago

Can u plz help me with this !!!

Mathematics

1 answer:

Sveta_85 [38]3 years ago

5 0

Answer:

Step-by-step explanation:

10 + 5 = 15. 15/2 is 7.5. 7.5 times 8 is 60. The formula for the area of the trapezoid is (a+b)/2 x h.

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Calculate the sample variance and sample standard deviation for the following frequency distribution of heights in centimeters f

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$\bar X = \frac{\sum_{i=1}^n X_i f_i}{n}= \frac{22026.1}{171}=128.81$

$s^2 = \frac{2839948.85- \frac{(22026.1)^2}{171}}{171-1}= 16.59$

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Step-by-step explanation:

For this case we can calculate the sample variance and deviation with the following table

Class Midpoint (Xi) fi Xi*fi Xi^2 *fi

120.6-123.6 122.1 17 2075.7 253443

123.7-126.7 125.2 49 6134.8 768077

126.8-129.8 128.3 29 3720.7 477365.8

129.9-132.9 131.4 41 5387.4 707904.4

133.0-136.0 134.5 35 4007.5 633158.8

___________________________________________

Total 171 22026.1 2839948.85

For this case we can calculate the mean or expected value with the following formula:

$\bar X = \frac{\sum_{i=1}^n X_i f_i}{n}= \frac{22026.1}{171}=128.81$

Now we can calculate the sample variance with the following formula:

$s^2 =\frac{\sum f_i X^2_i -[\frac{(\sum X_i f_i)}{n}]^2}{n-1}$

And if we replace we got:

$s^2 = \frac{2839948.85- \frac{(22026.1)^2}{171}}{171-1}= 16.59$

And the standard deviation would be the square root of the variance and we got:

$s= \sqrt{16.59}=4.07$

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5×4=20

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