Grouped frequency
Example 9 Deleted for CBSE Board 2024 Exams
Question 6 Important Deleted for CBSE Board 2024 Exams You are here
Example 6 Important Deleted for CBSE Board 2024 Exams
Example 8 Important Deleted for CBSE Board 2024 Exams
Question 5 Important Deleted for CBSE Board 2024 Exams
Last updated at April 16, 2024 by Teachoo
Ex15.1, 6 A teacher wanted to analyse the performance of two sections of students in a mathematics test of 100 marks. Looking at their performances, she found that a few students got under 20 marks and a few got 70 marks or above. So she decided to group them into intervals of varying sizes as follows: 0 โ 20, 20 โ 30โฆ 60 โ 70, 70 โ 100. Then she formed the following table: (i) Find the probability that a student obtained less than 20% in the mathematics test. Total number of students = 90 Students with less than 20% marks = Students who have 0 โ 20 marks = 7 Probability that a student obtained less than 20% = (๐๐ก๐ข๐๐๐๐ก๐ ๐คโ๐ ๐๐๐ก๐๐๐๐๐ ๐๐๐ ๐ ๐กโ๐๐ 20% ๐๐๐๐๐ )/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐ ๐ก๐ข๐๐๐๐ก๐ ) = 7/90 Ex15.1, 6 (ii) Find the probability that a student obtained marks 60 or above. Total number of students = 90 Students who have 60 marks or above = Students who have 60 โ 70 marks + Students who have 70 โ above marks = 15 + 8 = 23 Probability that a student obtained marks 60 or above. = (๐๐ก๐ข๐๐๐๐ก๐ ๐คโ๐ ๐๐๐ก๐๐๐๐๐ 60 ๐๐๐๐๐ ๐๐ ๐๐๐๐ฃ๐)/(๐๐๐ก๐๐ ๐๐ข๐๐๐๐ ๐๐ ๐ ๐ก๐ข๐๐๐๐ก๐ ) = 23/90