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Suppose that $X$ and $Y$ are independent random variables such that each is equal to $0$ with probability $.5$ and $1$ with probability $.5.$

Find $P(X+Y \leq 1)?$  (Answer up to $2$ decimals)
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Here it is given that P(X = 0) = P(Y = 0) = P(X =1) = P(Y=1) = 0.5.

To find : P(X+Y <= 1) so it means  X+Y = 0 or X+Y =1 is only possible

P(X+Y =0) = P(X=0) and P(Y= 0) = 0.5 * 0.5 = 0.25.

P(X+Y =1) = P(X=1) and P(Y= 0)  OR P(X=0) and P(Y= 1)  = 0.5 * 0.5  + 0.5 * 0.5= 0.25 + 0.25 =0.5

so final answer we will get, 0.5 + 0.25 = 0.75
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It should be  P(X = 0) = P(Y = 0) = P(X =1) = P(Y=1) = 0.5
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