I am trying to solve this question

I have been able to get the distribution function. the correct anwer given to me is that P( machine needs no replacement during the first 3 years) = 0.3.Let X be the number of years a particular type of machine is in good working condition and need no replacement. Assume that X has the probability mass function

P(1) = 0.4, P(2) = 0.3, P(3) = 0.2, P(4) = 0.08, P(5) = 0.02.

Find the distribution function F. Sketch F. Find the probability that the machine needs no replacement during the first 3 years.

However, from the distribution function F sketch, I get P(machine needs no replacement during the first 3 years) = 0.7.

what is the right answer for this? if 0.3, why is it so?

Thank you.

regards,

tommy