JEE PYQ: Probability Question 17
Question 17 - 2020 (03 Sep Shift 1)
A die is thrown two times and the sum of the scores appearing on the die is observed to be a multiple of 4. Then the conditional probability that the score 4 has appeared at least once is:
(1) $\frac{1}{4}$
(2) $\frac{1}{3}$
(3) $\frac{1}{8}$
(4) $\frac{1}{9}$
Show Answer
Answer: (4)
Solution
$E_1$: sum is multiple of 4 = ${4, 8, 12}$. Outcomes: $(1,3),(2,2),(3,1),(2,6),(3,5),(4,4),(5,3),(6,2),(6,6)$ = 9. $E_2$: 4 appears at least once with sum multiple of 4: $(4,4)$ only = 1. $P = \frac{1}{9}$.
BETA
