The probability distribution for the random variable x follows X.         f (x) 20.         0.21 25.      0.13 30.         0.30 36        0.36 a) what is the probability that...

 The probability distribution for the random variable x follows

X.         f (x)

20.         0.21

25.      0.13

30.         0.30

36        0.36

a) what is the probability that x=30 ( to 2 decimals)?

b) what is the probability that x is less than or equal to 25 ( to 2 decimal)?

c) what is the probability that x is greater than 30 ( to 2 decimal places)?

2 Answers | Add Yours

gsenviro's profile pic

gsenviro | College Teacher | (Level 1) Educator Emeritus

Posted on

Using the given probability distribution of the discrete variable, x:

1) Probability that x =30 is given as 0.30 (can be directly read from the given data). 

2) Probability that x is less than or equal to 25 = probability that x is less than 25 + probability that x is equal to 25 = 0.21 + 0.13 = 0.34

3) Probability that x is greater than 30 = 0.36 (Same as probability of x =36, since this is the only value of x, greater than 30, for which the value of f(x) is given.).

We can also cross-check the overall result. The 3 statements account for the probabilities of the instances of x less than 30, x equal to 30 and x greater than 30; which should obviously be 1 (as it covers all the possible values of x). The same is the sum of probabilities of the three cases.

hope this helps. 

We’ve answered 318,915 questions. We can answer yours, too.

Ask a question