Question

p(a) = 0.60, p(b) = 0.20, and p(a and b) = 0.15 what is p(a or b) choices: A. 0.12, B. 0.65, C. 0.40, or D. 0.80 (Note- This is on AP3X)

Answer 1

`p(a\ or\ b) = 0.65`

Explanation:

Given

`p(a) = 0.60`

`p(b) = 0.20`

`p(a\ and\ b) = 0.15`

Required

`p(a\ or\ b)`

The relationship between the given parameters and the required parameters is as follows;

`p(a\ and\ b) = p(a) + p(b) - p(a\ or\ b)`

Substitute values for the known parameters

`0.15 = 0.60 + 0.20 - p(a\ or\ b)`

`0.15 = 0.80 - p(a\ or\ b)`

Collect Like Terms

`p(a\ or\ b) = 0.80 - 0.15`

`p(a\ or\ b) = 0.65`

Hence;

`p(a\ or\ b) = 0.65`