Question:

In a class XII of a school, \(40\%\) of the students study Mathematics, \(30\%\) study Physics and \(20\%\) study Chemistry. \(20\%\) of the class study both Mathematics and Physics, \(10\%\) study both Mathematics and Chemistry and \(10\%\) study both Physics and Chemistry. \(5\%\) of the class study all the three subjects. If a student is selected at random from the class, find the probability that he studies neither Mathematics nor Physics nor Chemistry.

Show Hint

For three sets: \[ P(A\cup B\cup C) = P(A)+P(B)+P(C) -P(A\cap B) -P(B\cap C) -P(C\cap A) +P(A\cap B\cap C) \] Probability of none: \[ 1-P(A\cup B\cup C) \]
Updated On: Jun 16, 2026
  • \(0.55\)
  • \(0.65\)
  • \(0.35\)
  • \(0.45\)
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is D

Solution and Explanation

Concept: Use the Principle of Inclusion-Exclusion: \[\begin{aligned} n(M\cup P\cup C) &=n(M)+n(P)+n(C)\\ &\quad-n(M\cap P)-n(M\cap C)-n(P\cap C)\\ &\quad+n(M\cap P\cap C) \end{aligned}\]

Step 1: Substitute the given percentages. \[\begin{aligned} P(M\cup P\cup C) &=0.40+0.30+0.20\\ &\quad-0.20-0.10-0.10\\ &\quad+0.05 \end{aligned}\] \[\begin{aligned} &=0.55 \end{aligned}\]

Step 2: Find the probability of studying none of the subjects. \[\begin{aligned} P(\text{None}) &=1-P(M\cup P\cup C) \end{aligned}\] \[\begin{aligned} &=1-0.55 \end{aligned}\] \[\begin{aligned} &=0.45 \end{aligned}\] \[\begin{aligned} \boxed{0.45} \end{aligned}\] Hence, option \(\mathbf{(D)}\) is correct.
Was this answer helpful?
0
0