Question 925723
13 Questions: 10A, 3(not answered)
P(answering first two) = {{{(10/13)(9/12)}}}
P(first or the second but not both) = {{{(10/13)(3/12) + (3/13)(10/12)}}}
P(exactly 3 of the first 5 questions) = {{{(10C3)(3C2)/13C2)}}}
P( 3 0r 4 0r 5) = {{{ (10C3)(3C2)/(13C2) + (10C4)(3C1)/(13C2) +(10C5)(3C0)/(13C2) }}}