Download presentation

Presentation is loading. Please wait.

Published byBlake McDermott Modified over 4 years ago

1
**S1 Measures of Dispersion The mean, variance and standard deviation**

2
**S1 Measures of Dispersion**

Objectives: To be able to find the variance and standard deviation for discrete and continuous data using excel

3
**The marks scored in a test by seven students are 3,4,6,2,8,8,5**

The marks scored in a test by seven students are 3,4,6,2,8,8,5. Calculate the variance and standard deviation. x 3 4 6 2 8 5 Variance = Σx² – Σx ² n n _ x² 9 16 36 4 64 25 σ ² = 218 – 36 ² = 4.69 σ = √4.69 = 2.17 Σx = 36 Σx² = 218

4
**Variance and standard deviation of discrete data**

Variance = Σx² – Σx ² n n _ Use excel to quickly work out the variance and standard deviation of the questions below 3, 9, 12, 24, 10, 21, 27, 16 45, 56, 61, 34, 50, 50, 66, 51, 48, 49, 38 18, 22, 30, 27, 19, 25, 2, 156 Compare the answers you got in Q1 and 2 to the answer for Q3. Explain the difference

5
**The variance and standard deviation from a frequency table**

Number of rods (x) Freq of rods (f) 35 3 36 17 37 29 38 34 39 26 fx fx² 105 612 1073 1292 1014 3675 22032 39701 49096 39546 Σf=109 Σfx=4096 Σfx²=154050 Variance = Σfx² – Σfx ² Σf Σf Variance = – ² σ ²= σ = 1.109

6
**Use Excel to quickly work out the variance and standard deviation of the question below**

4 2 5 17 6 22 7 15 8 Variance = Σfx² – Σfx ² Σf Σf Change the frequency for x=4 or x=8. What happens to the standard deviation? What happens when you change the frequency when x=6? Explain why

7
**Variance and standard deviation from a grouped frequency distribution**

Height of plant (cm) Freq (f) 0 < h ≤ 5 4 5 < h ≤ 10 15 10 < h ≤ 15 5 15 < h ≤ 20 2 20 < h ≤ 25 25 < h ≤ 30 1 Total σ ² = – 285 ² = σ = √ σ = 11.35

8
**Describe the skewness of each of the data sets**

Use excel to work out the standard deviation for the following sets of data X F 8 13 9 21 10 37 11 35 12 4 X F 23 127 24 90 25 56 26 17 27 8 Height F 5-10 6 11-16 15 17-22 21 23-28 56 29-34 52 Height F 25-34 20 35-44 24 45-54 37 55-64 42 65-74 22 75-84 16 Comment on and compare the standard deviation for each of the data sets Describe the skewness of each of the data sets

Similar presentations

Presentation is loading. Please wait....

OK

MaK_Full ahead loaded 1 Alarm Page Directory (F11)

MaK_Full ahead loaded 1 Alarm Page Directory (F11)

© 2018 SlidePlayer.com Inc.

All rights reserved.

By using this website, you agree with our use of **cookies** to functioning of the site. More info in our Privacy Policy and Google Privacy & Terms.

Ads by Google

Ppt on neural networks Free ppt on arithmetic progression for class 10 Ppt on natural and artificial satellites and their uses Ppt on varactor diode testing Ppt on the road not taken analysis Ppt on brain computer interface Ppt on new technology in computers and mobiles Best ppt on body language Ppt on game theory wiki What to expect at 30 week dr appt on the beach