Given two events a and b of a sample set where p[a] = .20 p[not b] = .40 p[b|a] = .25 what is p[a or b]?

Given two events A and B of a sample set :-

P[A] = 0.20  

P[not B]=0.40

To find P[A or B]:

               ......[1]

Calculate for and

P[B] = 1- P[not B]

Substitute the value P[not B] we get;

P[B] = 1-0.40 = 0.60      

Substitute the given values we get;

Then;

Therefore, the value of P[A or B] is, 0.75.

the answer will be the last one

b

step-by-step explanation:

the word superfluous means unnecessary