100% of Kerion's paper squares are:
(100% / 100%) = 1
Half of the squares of your paper are colored blue:
(1) / (2) = 1/2
Of the blue squares, 1/3 of them will also have stripes:
(1/2) * (1/3) = 1/6
answer
A fraction of (1/6) squares will be blue with strips