Answer to Question #212540 in Statistics and Probability for Ghina

Question

Consider the random variable X and its probability mass function:

𝑋 70 80 90

𝑃(𝑋 = 𝑥) 0.3 0.45 0.25

a- Find the expected value of this random variable.

b- Find the cumulative distribution of this random.

c- Calculate P(𝑋 ≥ 80) in two methods: Use the cumulative distribution and the probability mass function.