## Solving Lesson 18 Page 38 Math Workbook 10 – Kite>

Topic

The forecast results of the highest temperature for 10 consecutive days in Nghe An at the end of January 2022 are given in the following table:

 Day 22 23 24 25 26 27 28 29 30 thirty first Temperature (degrees Celsius) 23 25 26 27 27 27 27 21 19 18

a) Write a sample of the temperature statistics obtained from the table above

b) Calculate the mean, variance, and standard deviation of that data sample

Solution method – See details

+ Write the data samples in non-increasing order

+ Use the formula to calculate the average: $$\overline x = \frac{{{x_1} + {x_2} + … + {x_n}}}{n}$$

+ Find the variance using the formula $${S^2} = \frac{1}{n}\left( {{n_1}{x_1}^2 + {n_2}{x_2}^2 + … + {n_k}) {x_k}^2} \right) – {\overline x ^2}$$ and standard deviation $$S = \sqrt {{S^2}}$$

Detailed explanation

a) Write data samples in non-increasing order: 23; 25; 26; 27; 27; 27; 26; 21; 19; 18

b)

+ The mean of the data sample is: $$\overline x = \frac{{23 + 25 + 26 + 27 + 27 + 27 + 26 + 21 + 19 + 18}}{{10}} = 24$$

+ Variance: $${S^2} = \frac{1}{{10}}\left( {{{23}^2} + {{25}^2} + … + {{18}^2 ) }} \right) – {24^2} = 11,2$$

+ Standard Deviation: $$S = \sqrt {{S^2}} = \sqrt {11,2} = \frac{{2\sqrt {70} }}{5}$$