Mathematics 4024 · O Level · Probability of combined events

Probability of combined events — practice question

George has two bags, and each bag contains black balls as well as white balls. A separate experiment uses counters in three colours.
(a(i))[2]

George says: I am more likely to take a black ball from bag 2 than from bag 1. Show that he is correct.

(a(ii))[2]

George chooses a ball at random from Bag 2, records its colour and then replaces it. He repeats this $220$ times. How many times would he expect to choose a white ball?

(b(i))[2]

A bag contains $7$ blue counters, $6$ red counters and $3$ green counters. Yasmin takes two counters at random without replacement. Complete the tree diagram.

(b(ii))[3]

Find the probability that at least one of the counters is red.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Accurate probability comparison

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