Question

the table given below shows the marks obtained by 80 students of a class in a test with maximum marks100
marks:-0-15,15-30,30-45,45-60,60-75, above 75
number of students:-6,13,17,24,16,4
a student of a class is selected at random. find the probability that he gets:-
(i) less than 15%
(ii)60 or more marks
(iii) less than 45 marks.​

Answer 1

(i) Number of favourable outcomes= 6

Total number of outcomes = 80

P(E1) = 6/80 = 3/40 = 0.075

(ii) Number of favourable outcomes= 16+4 = 20

Total number of outcomes = 80

P(E1) = 20/80 = 1/4 = 0.25

(iii) No. of favourable outcomes= 6+13+17 = 36

Total number of outcomes = 80

P(E1) = 36/80 = 9/20 = 0.45