Question

Giving a test to a group of students, the grades and gender are summarized below

A B C Total
Male 7 20 14 41
Female 3 4 19 26
Total 10 24 33 67


If one student is chosen at random,

Find the probability that the student was male OR got an "A".

Answer 1

46/ 67

Explanation:

The numbers of students irrespective of grades is;

The sum of the last roll of numbers:

10+24+ 33+ 67 = 134

The number of males irrespective of grades is the sum of the numbers in the male row ;

7 +20+ 14 +41= 82

The numbers of students with grade A is the first column at the last row and is 10;

Hence;

the probability that the student was male OR got an 'A' is

the probability that the student was male plus the probability that he/she got an 'A'.

The probability that it's a male is ;

Number of males/ total number of students

=82/134

The probability that he got an A is;

The number of students that got A/ the total number of students;

10/134

Hence

the probability that the student was male OR got an 'A' is;

82/ 134 + 10/134 = 92/134 = 46/ 67