SPM Practice (Short Questions)

Question 6:
A box contains blue marbles and green marbles. A marble is picked at random from the box.
The probability of picking a blue marble is

\frac{6}{11}

. If there are 30 green marbles in the box, how many blue marbles are there in the box?

Solution:
Probability of picking a green marble = 1 –

\frac{6}{11}

=

\frac{5}{11}

Total number of marbles in the box = 30 ×

\frac{11}{5}

= 66

Hence, number of blue marbles in the box = 66 – 30 = 36

Question 7:

Table below shows the distribution of a group of 90 pupils attending a penalty kick training programme.

A pupil is chosen at random from the group to start the penalty kick training.

What is the probability that a boy from Form Five will be chosen?

Solution:

P (a boy from Form Five)

= \frac{24}{90} = \frac{4}{15}

Question 8:

Diagram below shows some number cards.

A card is picked at random. State the probability that a prime number is picked.

Solution:

prime number = {11, 19, 37}
P (a prime number)

= \frac{3}{6} = \frac{1}{2}