STATISTICS (LECTURE 3)

STATISTICS_CLASS 10

  

Good Morning Students!

We have covered the following learning outcomes so far:

• Recall the different ways in which the data can be written
• Recall the measures of central tendencies
• Defined mode of the given data
• Calculate Mode of the given data
• Interpret Mode of the given data

Let us go through the guidelines for the  blog once again:

•              The text in Red, is to be written in your register

•              The text in blue is to be viewed by clicking on it

•              The text in green is to be practiced for home work

TO BEGIN 👇

1. take your SET-A Mathematics Note Book
2. Our handwriting reflects a lot about us. It will be awesome if you use good presentation and cursive hand writing. Hope you are still at it !!👍
3. Make a column on the right hand side, if you need to do any rough work
4. Leave two lines where you finished yesterday’s work and draw a horizontal line. Recall SDG-12 (turn the leaves of your notebooks to read that!) Thank you😄
5. Write today's date on the line after that. 
6. Please write the learning outcomes as mentioned below

I will be able to  :  

• Calculate CLASS MARKS for each class interval given in the data table.
• Calculate Mean for the grouped data using the DIRECT METHOD.
• Calculate Mean for the grouped data using the ASSUMED MEAN METHOD.                                                                       

Please click 👇

What is the first step to find mean for the grouped data ?

Q1)  If the class interval is (10 -15) then the lower limit is ___
                            { Hint: Which is the smaller number , 10 or 15 ?}

Q2)  If the class interval is (10 -15) then the upper limit is ___

                   { Hint: Which is the larger number , 10 or 15 ?}

Q3)  If the class interval is (10 -15) then the class mark is ___

                           { Hint: ADD the two limits and divide the SUM by 2}

Q4)  Calculate the class marks for each class interval in the following table: (make the table in the notebook)

Class Intervals	Frequency (fi)	Class Marks (xi)
0 -10	3
10-20	2
20-30	4
30-40	7
40-50	5

{Observation: The intervals given in Q4 are CONTINUOUS. 

             ⇒ upper limit of the 1st interval (10) = lower limit of the 2nd interval (10)  , and so on... }

Leave around 4 lines before starting Q5. We will come back to Q4 later to do something more to it! 😎

Q5)  Calculate the class marks for each class interval in the following table: (make the table in the notebook)

Class Intervals	Frequency (fi)	Class Marks (xi)
7 -11	318
12-16	112
17-21	401
22-26	227
27-31	325

{Observation: The intervals given in Q4 are DISCONTINUOUS. 

             ⇒ upper limit of the 1st interval (11) ≠ lower limit of the 2nd interval (12)  , and so on... }

And, it DOES NOT matter whether they are continuous or discontinuous. You simply find the values of  (x_i), using the hint given in Q3.

Now that you have calculated (x_i), you do not even need to look at your class interval column. All the remaining calculations will just involve :
(f_i) & (x_i)  Please click 👇

What to do after you have calculated the class marks (x_i) ?

Now that you have seen how to calculate the mean using :

• Direct Method
• Assumed Mean Method

Please use the following formulae to calculate mean using "direct method" and then using "assumed mean method" for Q4 & Q5   👇

Are you going to start over again ? NO !! 😡

Get back to where you did Q4. 

You already have 3 columns there ?

Make the 4th column with heading as (f_i x_i)

Do the calculations for the 4th column and use the formula for "direct method" to calculate the mean 👍

Now Make the 5th column with heading as (f_i d_i)

Do the calculations for the 5th column and use the formula for "assumed mean method" to calculate the mean👍

Home Work: NCERT Ex 14.1 (Q1,2,4,5,6)

“Facts 

are stubborn things, 

but 

statistics 

are pliable.”

― Mark Twain

So, here is the new word for you. Please write in your diary with today's date:

PLIABLE - means :easily influenced

We as global citizens need to be NOT PLIABLE and thus to do crazy things to harm mother earth.

Let us imbibe SDG-13 (Climate Action) in our lives by taking urgent action to combat climate change and its impacts

{It was Crazy to burn crackers, when we were just to light a candle or diya or torch on 5th April 2020 at 9pm}😔  

That will be all for today !

Thank you boys !  😊

See you in the next class on 8th April 2020 during your Maths slot

Take a good care of yourselves !