ECZ 2021 · O-Level Paper 2 · Question 1 — Probability
Question from ECZ 2021 · O-Level Paper 2 · Question 1
(a) Simplify a - 12a2 - 144.[2]
Verified working — step 1
a2 - 144 is a difference of two squares: (a - 12)(a + 12).(b) A box contains 3 black and 2 white marbles of the same size. A marble is taken out at random from the box and not replaced. A second marble is then drawn. Calculate the probability that both marbles are
(b(i)) white,[2]
Verified working — step 1
5 marbles, 2 white, drawn WITHOUT replacement.(b(ii)) of different colours.[3]
Verified working — step 1
"Different colours" is black-then-white or white-then-black:The full step-by-step working and final answer are included with Premium — checked against ECZ marking standards.
Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.
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