S.chand Composite Maths books class 8 maths solution chapter 28 Data Handling exercise 28 B

 EXERCISE 28 B

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Q1 | Ex-28B | Class 8 | SChand Composite Maths | Data Handling | myhelper

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Question 1

Fill in the blanks:
(i) The difference between the maximum and the minimum observations in a data is called the ___ of the data.

Sol : Range

(ii) The number of observations in a particular class interval is called the ___ of the class interval.

Sol : Frequency

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Q2 | Ex-28B | Class 8 | SChand Composite Maths | Data Handling | myhelper

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Question 2

Find:
(i) Lower limit of the class interval 46 - 53

Sol : 46

(ii) Upper limit of the class interval 30 — 35

Sol : 35

(iii) The range of the data 2 , 9 , 17 , 25 , 4 , 11

Sol : 23

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Q3 | Ex-28B | Class 8 | SChand Composite Maths | Data Handling | myhelper

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Question 3

Find the class marks of the following table:

Weights in kg	10-20	20-30	30-40	40-50	50-60
Class-marks	--	--	--	--	--

Sol :

Weights in kg	10-20	20-30	30-40	40-50	50-60
Class-marks	$=\dfrac{10+20}{2}=15$	$=\dfrac{20+30}{2}=25$	$=\dfrac{30+40}{2}=35$	$=\dfrac{40+50}{2}=45$	$=\dfrac{50+60}{2}=55$

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Q4 | Ex-28B | Class 8 | SChand Composite Maths | Data Handling | myhelper

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Question 4

The following are the monthly rents (in rupees) of 30 shops
42,49,37,82,37,75,62,54,79,84,75,63,44,74,36,69,54,48,74,39,48,45,61,71,47,38,80,51,31,47.

Using the class intervals of equal width in which one class interval being 40-50 (excluding 50) . Construct a frequency table for the above data .

Sol :

Monthly rent (in rupees)	30-40	40-50	50-60	60-70	70-80	80-90
f	6	8	3	4	6	3

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Q5 | Ex-28B | Class 8 | SChand Composite Maths | Data Handling | myhelper

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Question 5

On the first day of school , a school bus brought 40 students to a high school . Their wages were as follows:
13,11,9,10,15,6,5,8,15,16,17,7,8,10,13,17,14,12,14,13,6,11,9,10,12,17,16,7,8,9,6,10,6,8,13,9,6,8,12
Group the ages into four equal classes with class intervals 4-8 etc and construct a frequency table

Sol :

Age	4-8	8-12	12-16	16-20
f	8	15	12	5

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Q6 | Ex-28B | Class 8 | SChand Composite Maths | Data Handling | myhelper

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Question 6

Find the mean of each of the following frequency distributions.

Class	0-10	10-20	20-30	30-40	40-50	50-60	60-70
Frequency	4	4	7	10	12	8	5

Sol : 

Class Interval	Frequency(f)	Class Marks(x)	f.x
0-10	4	$\dfrac{0+10}{2}=5$	4×5=20
10-20	4	$\dfrac{10+20}{2}=15$	4×15=60
20-30	7	$\dfrac{20+30}{2}=25$	7×25=175
30-40	10	$\dfrac{30+40}{2}=35$	10×35=350
40-50	12	$\dfrac{40+50}{2}=45$	12×45=540
50-60	8	$\dfrac{50+60}{2}=55$	8×55=440
60-70	5	$\dfrac{60+70}{2}=65$	5×65=325
	𝝨f =50		𝝨fx=1910

$\overline{x}=\dfrac{\sum fx}{\sum f}=\frac{1910}{50}$

=38.2