Question

P(e1)=P(e2)=0.15

P(e3)=0.4

P(e4)=2*P(e5)

What is P(e5) and P(e4)?

Answer 1

the sum of the probabilities is always 1

so at the moment if there are 5 events in the sample space then

P(e1) + P(e2) + P(e3) = 0.7

then

P(e4) + P(e5) = 0.3 (1)

and you know P(e4) = 2*P(e5) (2)

so making a substitution of (2) into equation (1)

you have

2*P(e5) + P(e5) = 0.3

or

3P(e5) = 0.3

you should be able to solve for P(e5) and also find P(e4) by putting your solution into (2)