The probability distribution for the random variable x follows
X. f (x)
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)?
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.