JEE Advance - Mathematics (1986 - No. 27)
If $${{1 + 3p} \over 3},\,\,\,{{1 - p} \over 4}$$ and $$\,{{1 - 2p} \over 2}$$ are the probabilities of three mutually exclusive events, then the set of all values of $$p$$ is ..............
$$p \le 1/2$$
$$-1/3 \le p \le 1/2$$
$$1/3 \le p \le 1/2$$
$$p \ge -1/3$$
$$p \ge 1/2$$