statistics
posted by yvonne .
Identify why this assigbment if probabilities cannot be legitimite: P(A)=0.4, P(B)=0.3, P(AandB)= 0.5

Dont know what you're trying to say from "Identify why this assigbment if probabilities cannot be legitimite"...
by P(AandB) do you mean P(A intercept B) or P(A union B)? 
The probability of both/all events occurring is found by multiplying the probabilities of the individual events.
.4 * .3 ≠ .5