The probability that bulbs selected randomly from the lot has life less than 900 hours is :
Life time (in hours) 300 500 700 900 1100
Frequency 10 12 23 25 10
a. 11/40
b. 5/16
c. 7/16
d. 9/16

Solution:

It is given that

Total number of bulbs in a lot n(S) = 80

Number of bulbs whose life time is less than 900 hours n(E) = 10 + 12 + 23 = 45

We know that

Probability that bulbs selected randomly from the lot has life less than 900 hours = n(E)/n(S)

Substituting the values

= 45/80

= 9/16

Therefore, the probability that bulbs selected randomly from the lot have life less than 900 hours is 9/16.

✦ Try This: Median of the following numbers : 5, 5, 7, 8, 6, 9, 9, 4, 2 is

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

NCERT Exemplar Class 9 Maths Exercise 14.1 Problem 30

The probability that bulbs selected randomly from the lot have life less than 900 hours is : Life time (in hours) 300 500 700 900 1100 Frequency 10 12 23 25 10 a. 11/40, b. 5/16, c. 7/16, d. 9/16

Summary:

The probability that bulbs selected randomly from the lot have life less than 900 hours is 9/16

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