In a medical examination of students of a class, the following blood groups are recorded:
Blood group A AB B O
Number of students 10 13 12 5
A student is selected at random from the class. The probability that he/she has blood group B, is:
a. 1/4
b. 13/40
c. 3/10
d. 1/8

Solution:

It is given that

Total number of students in a medical examination n(S) = 40

Number of students who have B blood group n(E) = 12

We know that

Probability that he/she has blood group B = n(E)/n(S)

Substituting the values

= 12/40

= 3/10

Therefore, the probability that he/she has blood group B is 3/10.

✦ Try This: In a survey of 125 children aged 10-15 months, it was found that 21 liked to eat potato chips. If a child is selected at random, the probability that he/she does not like to eat potato chips is :

☛ Also Check: NCERT Solutions for Class 9 Maths Chapter 14

NCERT Exemplar Class 9 Maths Exercise 14.1 Problem 27

In a medical examination of students of a class, the following blood groups are recorded: Blood group A AB B O Number of students 10 13 12 5. A student is selected at random from the class. The probability that he/she has blood group B, is: a. 1/4, b. 13/40, c. 3/10, d. 1/8

Summary:

In a medical examination of students of a class, the following blood groups are recorded. A student is selected at random from the class. The probability that he/she has blood group B, is 3/10

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