Question 6 (i)
A teacher wanted to analyze 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 : 0−20,20−30…60−70,70 − 100. Then she formed the following table:
MarksNumber of student0−20720−301030−401040−502050−602060−701570−above8Total90
(i) Find the probability that a student obtained less than 20% in the mathematics
test.
Total number of students = 90
(i) Number of students getting less than 20 % marks in the test = 7
Hence, required probability, P=790