     1. Chapter 16 Class 11 Probability
2. Serial order wise
3. Miscellaneous

Transcript

Misc 8 From the employees of a company, 5 persons are selected to represent them in the managing committee of the company. Particulars of five persons are as follows: A person is selected at random from this group to act as a spokesperson. What is the probability that the spokesperson will be either male or over 35 years? Total number of persons = 5 So, n(S) = 5 Probability spokesperson is male Let A be the event that person selected is male There are 3 males So, n(A) = 3 Probability spokesperson is male = P(A) = ( ) ( ) = 3 5 Probability spokesperson is over 35 years old Let B be the event that person selected is over 35 There are 2 person over 35 years old So, n(B) = 2 Probability spokesperson is over 35 years old = P(B) = n(B) n(S) = 2 5 We need to find probability that the spokesperson will be either male or over 35 year i.e. P(A B) We know that P(A B) = P(A) +P(B) P(A B) To find P(A B), we must find P(A B) first P(A B) Probability that spokesperson is male & over 35 years old Here, 1 person is both male & over 35 years old So, n(A B) = 1 P(A B) = ( ) ( ) = 1 5 Now, P(A B) = P(A) +P(B) P(A B) = 3 5 + 2 5 1 5 = 3 + 2 1 5 = 4 5 Hence Probability that the spokesperson will be either male or over 35 year = P(A B) = 4 5

Miscellaneous 