Solved on Dec 17, 2023

Find the standard error of the sample mean for the daily high temperatures (in °\degreeF) in Des Moines over 1 week: Monday (64.5), Tuesday (64), Wednesday (66.5), Thursday (64), Friday (62.5), Saturday (61), Sunday (63).

STEP 1

Assumptions
1. The temperatures given are the daily high temperatures for Des Moines for a week.
2. We are to calculate the standard error of the sample mean.
3. The standard error of the sample mean is given by the formula: SE=sn SE = \frac{s}{\sqrt{n}} where s s is the sample standard deviation and n n is the sample size.

STEP 2

First, we need to calculate the sample mean temperature. The sample mean is given by the formula: xˉ=xin \bar{x} = \frac{\sum{x_i}}{n} where xi x_i represents each temperature value and n n is the number of temperature values.

STEP 3

Now, plug in the given temperature values to calculate the sample mean.
xˉ=64.5+64+66.5+64+62.5+61+637 \bar{x} = \frac{64.5 + 64 + 66.5 + 64 + 62.5 + 61 + 63}{7}

STEP 4

Calculate the sample mean temperature.
xˉ=445.57 \bar{x} = \frac{445.5}{7}
xˉ=63.64 \bar{x} = 63.64 (rounded to two decimal places)

STEP 5

Next, we need to calculate the sample variance. The sample variance s2 s^2 is given by the formula: s2=(xixˉ)2n1 s^2 = \frac{\sum{(x_i - \bar{x})^2}}{n - 1}

STEP 6

Calculate the squared differences between each temperature value and the sample mean.
(64.563.64)2=0.862=0.7396 (64.5 - 63.64)^2 = 0.86^2 = 0.7396 (6463.64)2=0.362=0.1296 (64 - 63.64)^2 = 0.36^2 = 0.1296 (66.563.64)2=2.862=8.1796 (66.5 - 63.64)^2 = 2.86^2 = 8.1796 (6463.64)2=0.362=0.1296 (64 - 63.64)^2 = 0.36^2 = 0.1296 (62.563.64)2=1.142=1.2996 (62.5 - 63.64)^2 = -1.14^2 = 1.2996 (6163.64)2=2.642=6.9696 (61 - 63.64)^2 = -2.64^2 = 6.9696 (6363.64)2=0.642=0.4096 (63 - 63.64)^2 = -0.64^2 = 0.4096

STEP 7

Sum the squared differences to find the numerator for the sample variance.
(xixˉ)2=0.7396+0.1296+8.1796+0.1296+1.2996+6.9696+0.4096 \sum{(x_i - \bar{x})^2} = 0.7396 + 0.1296 + 8.1796 + 0.1296 + 1.2996 + 6.9696 + 0.4096
(xixˉ)2=17.8572 \sum{(x_i - \bar{x})^2} = 17.8572

STEP 8

Now, divide the sum of squared differences by n1 n - 1 to find the sample variance.
s2=17.857271 s^2 = \frac{17.8572}{7 - 1}
s2=17.85726 s^2 = \frac{17.8572}{6}
s2=2.9762 s^2 = 2.9762 (rounded to four decimal places)

STEP 9

Take the square root of the sample variance to find the sample standard deviation.
s=s2 s = \sqrt{s^2}
s=2.9762 s = \sqrt{2.9762}
s=1.7252 s = 1.7252 (rounded to four decimal places)

STEP 10

Finally, calculate the standard error of the sample mean using the sample standard deviation and the sample size.
SE=sn SE = \frac{s}{\sqrt{n}}
SE=1.72527 SE = \frac{1.7252}{\sqrt{7}}
SE=1.72522.6458 SE = \frac{1.7252}{2.6458} (rounded to four decimal places for the square root of 7)

STEP 11

Calculate the standard error of the sample mean.
SE=0.6519 SE = 0.6519 (rounded to four decimal places)
Rounded to the hundredths place, the standard error of the sample mean is approximately 0.65 0.65 .

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