Need for Dividing Data into Classes

Q.

Prepare a frequency distribution table for the scores given:

42, 22, 55, 18, 50, 10, 33, 29, 17, 29, 29, 27, 34, 15, 40, 42, 40, 41, 35, 27,

44, 31, 38, 19, 54, 55, 38, 19, 20, 30, 42, 59, 15, 19, 27, 23, 40, 32, 28, 51.

Take the class intervals as 10-20, 20-30, 30-40, 40-50, 50-60.

From the frequency distribution table answer the following questions:

(i) What does the frequency corresponding to the class interval 20-30 indicate?

(ii) In which class intervals are the scores 10, 20 and 30 included?

(iii) Find the range of the scores.

Q.

The mid-point of a class-interval is called?

1. Class mark

2. Class width

3. Class interval

4. Class length

Q.

The class mark of the class with the highest frequency is

1. 55.5

2. 58

3. 60.5

4. 45.5

Q.

The histogram below represents marks of students in a Mathematics exam with passing marks as 30. For finding the number of failed students, what is the class interval that needs to be considered?

1. 15 - 30
2. 0 - 30
3. 15 - 45
4. 30 - 100

Q.

Class mark of a particular class is 7.5 and the class size is 8, then the class interval is

1. 3.5 - 15.5

2. 12.5 - 18.5

3. 3.5 - 11.5

4. 15.5 - 27.5

Q.

Upper limit of class interval $75–85$ is

1. $10$

2. $-10$

3. $75$

4. $85$

Q.

Assertion: We find midpoints of a class interval with the following formula.
$\frac{upperclasslimit+lowerclasslimit}{2}$

Reason: To draw frequency polygons independently without drawing histogram it is required to have the class mark.

Which of the following is correct?

1. Both A and R are true, but R is not the correct explanation of A

2. A is false and R is true

3. A is true and R is false

4. Both A and R are true and R is the correct explanation of A

Q. Find the mode of the digits used in writing the natural numbers from 11 to 30.

1. 3
2. 2
3. 1
4. 0

Q. The number of hours for which students of a particular class watched television during holidays is shown in the given graph.
We draw the histogram for above frequency table:
Answer the following:

How many students watched TV for less than 4 hours?

Q.

Arrange the given heights of 20 students in grouped distribution with a class interval of 5 and find the number of students above the height of 169cm.

Heights (in cm): 150, 153, 162, 170, 186, 153, 162, 180, 165, 150, 178, 156, 184, 176, 173, 186, 159, 183, 180, 156.

1. 10

2. 7

3. 9

4. 15

Q.

Draw a histogram for the frequency table made for the data in Question 3 and answer the following questions.

(i) Which group has the maximum number of workers?

(ii) How many workers earn Rs 850 and more?

(iii) How many workers earn less than Rs 850?

Q. Simplify $(-90)\times 52+(-52)\times (-25)$ using a suitable frequency.

Q.

What will be the first class interval, if the fifth class interval is $68-72$, the fourth class interval is $64-68$?

1. 
2. 
3. 
4. 

Q. Pair the values with corresponding terms for the class interval $3-7$.

1. 3
2. 4
3. 7
4. Lower limit
5. Upper limit
6. Class interval

Q.

Question 105(iii)

The following histogram shows the frequency distribution of teaching experiences of 30 teachers in various schools :

How many teachers have teaching experience of 10 to 20 years ?

Q. The number of hours for which students of a particular class watched television during holidays is shown in the given graph.
We draw the histogram for above frequency table:
Answer the following:

How many students spend more than 5 hours in watching TV?

Q. The following figure shows a histogram and corresponding frequency polygon. The data shows the number of victims suffering from a disease 'X' in various months of 2012.

Find the month having highest number of victims.

Q. Choose the correct pair of class interval and the data that can be included in that class interval.

1. 0-10
2. 10-20
3. 40-60
4. 10
5. 50
6. 5

Q. The number of hours for which students of a particular class watched television during holidays is shown in the given graph.
We draw the histogram for above frequency table:
Answer the following:

How many students watched TV for less than 4 hours?

Q. The number of hours for which students of a particular class watched television during holidays is shown in the given graph.
We draw the histogram for above frequency table:
Answer the following:

How many students spend more than 5 hours in watching TV?

Q.

The following histogram shows the frequency distribution of teaching experiences of 30 teachers in various schools :

The number of teachers with 5 to 10 years experience is

1. 15

2. 10

3. 16

4. 17

Q.

What is the width of the class interval 50-90?

1. 50

2. 60

3. 30

4. 40