Question 1: All the cards written with the letters from the word ‘INTERNATIONAL’ are put into a box. Two cards are drawn at random from the box, one after another, without replacement. Calculate the probability that (a) the first card drawn has a letter N and the second card drawn has a letter I. (b) … Read more

Question 1: A bag contains 36 marbles which are black and white. It is given that the probability for a black marble being picked at random from the bag is 5 9 . Calculate the number of white marbles to be taken out from the bag so that the probability of picking a black marble … Read more

9.3 Probability of a Combined Event   9.3b Finding the Probability of Combined Events (a) A or B (b) A and B 1. The probability of a combined event ‘A or B’ is given by the formula below.   P(A or B)=P(A∪B)     = n(A∪B) n(S)      2. The probability of a combined event ‘A and B’ is given … Read more

9.3 Probability of a Combined Event   9.3a Finding the Probability of a Combined Event by Listing the Outcomes 1. A combined event is an event resulting from the union or intersection of two or more events. 2. The union of combined event ‘A or B’ = A υ B 3. The intersection of combined event ‘A and B’ = A ∩ … Read more

9.2 Probability of the Complement of an Event 1. The complement of an event A is the set of all the outcomes in the sample space that are not included in the outcomes of event A. 2. The probability of the complement of event A is: P ( A ‘ ) = 1 − P … Read more

9.1 Probability of an Event The probability of an event A, P(A) is given by P ( A ) = Number of times event A occurs Number of trials P ( A ) = n ( A ) n ( S ) where 0 ≤ P ( A ) ≤ 1   If P(A) = … Read more