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MathematicsClass 84.1 Looking for Information

4.1 Looking for Information | Class 8 Mathematics Notes

By ConceptScroll Team · Published on 17 July 2026 · 5 min read

4.1 Looking for Information – this guide gives you a concise, exam-ready overview of 4.1 Looking for Information from Class 8 Mathematics, written by ConceptScroll editors and reviewed against the latest NCERT textbook.

Probability

This section introduces the concept of probability as a measure of how likely an event is to occur. It explains that probability is expressed as a number between 0 and 1, where 0 means the event cannot happen and 1 means the event is certain to happen. The section uses simple examples such as tossing a coin or rolling a die to illustrate the idea of equally likely outcomes. It defines an event as a specific outcome or set of outcomes from a random experiment. The section explains how to calculate the probability of an event by dividing the number of favorable outcomes by the total number of possible outcomes. It also discusses the difference between theoretical probability (based on reasoning) and experimental probability (based on actual trials). The section highlights that probability helps in making predictions and informed decisions in uncertain situations. It also introduces the idea that the sum of probabilities of all possible outcomes of an experiment is always 1. By the end of the section, students understand the basic principles of probability and how to apply them to simple problems.

📊 Diagram: The section includes diagrams of a coin showing heads and tails and a die with six faces to illustrate possible outcomes and calculation of probability.

🧪 Activity: Activity: Students toss a coin 20 times, record the number of heads and tails, and calculate the experimental probability of getting heads.

🔗 Connection: This section connects to the next part of the chapter where students explore more complex problems involving probability and use data to predict outcomes.

Frequently asked questions

1. A survey was made to find the type of music that a certain group of young people liked in a city. Adjoining pie chart shows the findings of this survey. From this pie chart answer the following: (i) If 20 people liked classical music, how many young people were surveyed? (ii) Which type of music is liked by the maximum number of people? (iii) If a cassette company were to make 1000 CD's, how many of each type would they make?

Solution:

Let the total number of young people surveyed be N.

(i) From the pie chart, classical music sector corresponds to 90°.

Since total angle in pie chart = 360°, the fraction of people liking classical music = 90/360 = 1/4.

Given number of people liking classical music = 20.

So, (1/4) N = 20 => N = 20 4 = 80.

Therefore, total number of young people surveyed = 80.

(ii) From the pie chart, the sector with the largest angle corresponds to pop music (120°).

Hence, pop music is like

2. A group of 360 people were asked to vote for their favourite season from the three seasons rainy, winter and summer. (i) Which season got the most votes? (ii) Find the central angle of each sector. (iii) Draw a pie chart to show this information.

Solution:

Given total people = 360

Votes:

  • Summer = 90
  • Rainy = 120
  • Winter = 150

(i) Season with most votes = Winter (150 votes).

(ii) Central angle for each sector = (Number of votes / Total votes) * 360°

  • Summer: (90/360)*360 = 90°
  • Rainy: (120/360)*360 = 120°
  • Winter: (150/360)*360 = 150°

(iii) To draw the pie chart:

  • Draw a circle.
  • Use a protractor to measure and draw sectors of 90°, 120°, and 150° corresponding to Summer, Rainy, and Winter respectively.
  • Label each sector a
3. Draw a pie chart showing the following information. The table shows the colours preferred by a group of people. Colours: Blue - 18, Green - 9, Red - 6, Yellow - 3, Total - 36

Solution:

Total number of people = 36

Calculate central angle for each colour:

  • Blue: (18/36)*360 = 180°
  • Green: (9/36)*360 = 90°
  • Red: (6/36)*360 = 60°
  • Yellow: (3/36)*360 = 30°

To draw the pie chart:

  • Draw a circle.
  • Use a protractor to mark sectors of 180°, 90°, 60°, and 30° for Blue, Green, Red, and Yellow respectively.
  • Label each sector with the colour name and number of people.
4. The adjoining pie chart gives the marks scored in an examination by a student in Hindi, English, Mathematics, Social Science and Science. If the total marks obtained by the students were 540, answer the following questions. (i) In which subject did the student score 105 marks? (Hint: for 540 marks, the central angle = 360°. So, for 105 marks, what is the central angle?) (ii) How many more marks were obtained by the student in Mathematics than in Hindi? (iii) Examine whether the sum of the marks obtained in Social Science and Mathematics is more than that in Science and Hindi. (Hint: Just study the central angles).

Solution:

Total marks = 540

Central angle for total marks = 360°

(i) Central angle corresponding to 105 marks = (105/540)*360 = 70°

From the pie chart, the sector with 70° corresponds to English.

Therefore, the student scored 105 marks in English.

(ii) Marks in Mathematics correspond to 120°.

Marks in Hindi correspond to 90°.

Marks in Mathematics = (120/360)*540 = 180

Marks in Hindi = (90/360)*540 = 135

Difference = 180 - 135 = 45 marks

(iii) Marks in Social Science = 90° => (90/360)*

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