Question

Find the missing probability.
P(A) = 0.4; P(B) = 0.7; P(A or B)
; P(A and B) = 0.3

Answer 1

Given:

`P(A)=0.4, P(B)=0.7, P(A\text{ and }B)=0.3`

To find:

The value of
`P(A\text{ or }B)`.

Solution:

We know that,

`P(A\text{ and }B)=P(A\cap B)`

`P(A\text{ or }B)=P(A\cup B)`

It means, we have
`P(A)=0.4, P(B)=0.7, P(A\cap B)=0.3` and we need to find the value of
`P(A\cup B)`.

`P(A\cup B)=P(A)+P(B)-P(A\cap B)`

`P(A\cup B)=0.4+0.7-0.3`

`P(A\cup B)=1.1-0.3`

`P(A\cup B)=0.8`

Therefore, the value of
`P(A\text{ or }B)` is 0.8.