Probability 2 ( O'level Revision)

A bag contains 4 red marbles and 2 yellow marbles.

Behnaz picks two marbles at random without replacement.

Find the probability that

(i) the marbles are both red,

• $\frac{2}{5}$

• $\frac{2}{3}$

• $\frac{1}{3}$

A bag contains 4 red marbles and 2 yellow marbles.

Behnaz picks two marbles at random without replacement.

Find the probability that

(ii) the marbles are not both red.

• $\frac{2}{5}$

• $\frac{3}{5}$

• $\frac{12}{30}$

Another bag contains 5 blue marbles and 2 green marbles.

Bryn picks one marble at random without replacement.

If this marble is not green, he picks another marble at random without replacement.

He continues until he picks a green marble.

Find the probability that he picks a green marble on his first, second or third attempt

• $\frac{5}{7}$

• $\frac{2}{5}$

• $\frac{3}{5}$

The diagram shows 5 cards.

(a) Donald chooses a card at random.

(i) Write down the probability that the number of dots on this card is an even number.

• $\frac{4}{5}$

• $\frac{2}{3}$

• $\frac{1}{5}$

The diagram shows 5 cards.

(a) Donald chooses a card at random.

(ii) Write down the probability that the number of dots on this card is a prime number.

• $\frac{1}{5}$

• $\frac{4}{5}$

• $\frac{3}{5}$

(b) Donald chooses two of the five cards at random, without replacement.

He works out the total number of dots on these two cards.

(i) Find the probability that the total number of dots is 5.

• $\frac{3}{10}$

• $\frac{3}{20}$

• $\frac{4}{19}$

(b) Donald chooses two of the five cards at random, without replacement.

He works out the total number of dots on these two cards.

(ii) Find the probability that the total number of dots is an odd number.

• $\frac{2}{5}$

• $\frac{3}{5}$

• $\frac{2}{3}$

The diagram shows five cards.

Two of the cards are taken at random, without replacement.

Find the probability that both cards show an even number.

• $\frac{1}{10}$

• $\frac{2}{3}$

• $\frac{1}{5}$

The probability that it will rain tomorrow is  $\frac{5}{8}$ .If it rains the probability that Rafael walks to school is  $\frac{1}{6}$  If it does not rain, the probability that Rafael walks to school is  $\frac{7}{10}$  

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Another bag contains 2 green counters and 3 pink counters.

Teresa chooses three counters at random without replacement.

Find the probability that she chooses more pink counters than green counters.

• $\frac{7}{10}$

• $\frac{7}{14}$

• $\frac{3}{4}$