You should use binomial deviation, i've got the exam upcoming monday myself
You should use binomial because there's two options: You either 'win' or 'lose' (receive gift or not)
To receive gift --> 1/4 --> 0,25
To NOT receive gift --> 3/4 --> 0,75
He buys 2 packages, so it has 2 trials.
Because you want to know an exact value, you'll use BinomPdf (P for precision)
So you'd have to fill in --> binomPdf(2;0,25;2) = 0,0625