No. 28
ADDITIONAL EXERCISE
Total outcomes = (1, 1), (1, 2), (1, 3), (1, 4), (1, 5), (1, 6),
The sample space when a fair die is tossed twice.
Q.] Find the probability of a four turning up at least once
in two tosses of a fair die.
(2, 1), (2, 2), (2, 3), (2, 4), (2, 5), (2, 6),
(3, 1), (3, 2), (3, 3), (3, 4), (3, 5), (3, 6),
(4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6),
(5, 1), (5, 2), (5, 3), (5, 4), (5, 5), (5, 6),
(6, 1), (6, 2), (6, 3), (6, 4), (6, 5), (6, 6).
Total possible outcomes = 36
Let A be the event of getting 4 at least once in two tosses of a fair die.
(1, 4), (2, 4), (3, 4), (4, 1), (4, 2), (4, 3), (4, 4), (4, 5), (4, 6), (5, 4), (6, 4)
No. of favorable outcomes = 11
∴ P (A) =
∴ P (A)
Either on 1st die
or on 2nd die
or on both the dice
Probability of event A is
Favourable elements of A are
11
36
=
Sol.
No. of favorable outcomes
Total possible outcomes
Total possible outcomes are
The number 4 should
appear at least once
The given event is