NCERT Class X Chapter 14: Probability Example 7

NCERT Class X Chapter 14: Probability Example 7

Question:

There are 40 students in Class X of a school of whom 25 are girls and 15 are boys. The class teacher has to select one student as a class representative. She writes the name of each student on a separate card, the cards being identical. Then she puts cards in a bag and stirs them thoroughly. She then draws one card from the bag. What is the probability that the name written on the card is the name of (i) a girl? (ii) a boy?

Given:

Total number of students = 40
Number of girls = 25
Number of boys = 15

To Find:

(i) Probability of selecting a girl
(ii) Probability of selecting a boy

Formula:

Probability = Number of favorable outcomes Total number of possible outcomes

Solution:

(i) Probability of selecting a girl:

Number of favorable outcomes (girls) = 25
Total number of possible outcomes (students) = 40
Probability (girl) = 25 40 = 5 8

(ii) Probability of selecting a boy:

Number of favorable outcomes (boys) = 15
Total number of possible outcomes (students) = 40
Probability (boy) = 15 40 = 3 8

Result:

(i) The probability that the selected student is a girl is 5 8 .
(ii) The probability that the selected student is a boy is 3 8 .

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