Question

The graph shows the probability distribution of a random variable.

What is the value of P(4≤X≤8)?

0.40
0.45
0.50
0.55

Answer 1

The answer is 0.50.

P(4<=X<=8)=P(x=4)+ P(x=5)+ P(x=6)+ P(x=7)+ P(x=8)= 0.05+ 0.15+0.15+0.15 +0 = 0.50

Notice that in 8 the line touches the x axis so it’s corresponding probability is 0.

Answer 2

The value of the defined probability, P(4≤X≤8) is 0.65

The probability P(4≤X≤8) can be explicitly written as ;

• P(4≤X≤8) = P(4) + P(5) + P(6) + P(7) + P(8)

From the probability distribution graph;

P(4) + P(5) + P(6) + P(7) + P(8) = 0.05 + 0.15 + 0.15 + 0.15 + 0.15 = 0.65

Hence, the value of P(4≤X≤8) is 0.60