Q. In a college, 25% of the boys and 10% of the girls offer Mathematics. The girls constitute 60% of the total number of students. If a student is selected at random and is found to be studying Mathematics. The probability that the student is a girl is
A) 1/6
B) 3/8
C) 5/8
D) 5/6
Explanation
(b)
Let total number of students be 100 in which 60% girls and 40% boys.
Number of boys =40,number of girls =60
25% of boys offer Mathematics $= \frac{25}{100} \times 40 = 10$ boys
10% girls offer Mathematics $= \frac{10}{100} \times 60 = 6$ girls
It means, 16 students offer Mathematics.
$\therefore$ Required probability $= \frac{6}{16} = \frac{3}{8}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.