# probability distribution

• May 30th 2007, 06:23 AM
nisoo-1
probability distribution
Q:1 A discrete random variable x can assume five possible values: 2, 3, 5, 8 and 10. Its probability distribution is shown here:

x= 2, 3, 5, 8 , 10.
p(x)=0.15, 0.10, --- 0.25, 0.25

1.What is p(5)?
2.What is the probability that x equals 2 or 10?
• May 30th 2007, 06:38 AM
CaptainBlack
Quote:

Originally Posted by nisoo-1
Q:1 A discrete random variable x can assume five possible values: 2, 3, 5, 8 and 10. Its probability distribution is shown here:

x= 2, 3, 5, 8 , 10.
p(x)=0.15, 0.10, --- 0.25, 0.25

1.What is p(5)?
2.What is the probability that x equals 2 or 10?

1. As $\sum_{i=1}^N p(x_i) = 1$ where the summation is over all the posible cases.

The given values of $p(x_i)$ sum to $0.75$, so the missing value id $0.25$

2. $P(x=2 \mbox{ or }x=10)=P(x=2) + P(x=10) = 0.15+0.25 = 0.4$.

RonL
• May 30th 2007, 06:50 AM
nisoo-1
Probability Distribution
Dear Sir,
which formula will be use to calculate this question?
• May 30th 2007, 11:30 AM
CaptainBlack
Quote:

Originally Posted by nisoo-1
Dear Sir,
which formula will be use to calculate this question?

There is no formula to calculate these, what you need is to understand the
concepts:

A. The sum of the probabilities of all the possible simple outcomes (a simple
outcome here means an element of the sample space) is 1.

B. The probability of one of a number of distinct simple outcomes occurring
is the sum of the probabilities of the individual simple outcomes.

RonL