Question 1041069
The random variable X = the number of questions she answers correctly.

==> The possible values of X are 0, 1, 2, 3, 4.

The probability distribution of X:

{{{P(X = 0) = (matrix(2,1,4,0))*0.80^4*0.20^0 = 0.4096}}}
{{{P(X = 1) = (matrix(2,1,4,1))*0.80^3*0.20^1 = 0.4096}}}
{{{P(X = 2) = (matrix(2,1,4,2))*0.80^2*0.20^2 = 0.1536}}}
{{{P(X = 3) = (matrix(2,1,4,3))*0.80^1*0.20^3 = 0.0256}}}
{{{P(X = 4) = (matrix(2,1,4,4))*0.80^0*0.20^4 = 0.0016}}}