Home / CIE iGCSE Maths E8.3 Probability of combined events Exam Style Practice Questions- Paper 2

CIE iGCSE Maths E8.3 Probability of combined events Exam Style Practice Questions- Paper 2

CIE iGCSE Maths E8.3 Probability of combined events Exam Style Practice Questions- Paper 2

Question

The Venn diagram shows information about the number of students in a class.

Some study English $(E)$, some study French $(F)$, some study Spanish $(S)$ and some do not study any of

these languages.

(a) Find n$((E\cup F)^\prime\cup S)$.

(b) One student is picked at random from those who study Spanish.

Find the probability that this student studies exactly two languages.

▶️Answer/Explanation

(a) $15$

(b) $\frac{1}{2}$

Only English → 8
Only French → 6
Both English and French → 1
English and Spanish → 2
French and Spanish → 3
All three languages → 1

(a)
Students not studying English or French:
$
(E \cup F)’ = 4 + 5 = 9
$
\( (E \cup F)’ \cup S \) – students not in English or French OR those in Spanish.
Students in Spanis
$
2 + 3 + 1 + 4 = 10
$
Combine with those outside \( E \cup F \)
$
n((E \cup F)’ \cup S) = 4 + 5 + 2 + 3 + 1 = 15
$

(b)

Total students studying Spanish:

$
2 + 3 + 1 + 4 = 10
$

English and Spanish (but not French) → 2
French and Spanish (but not English) → 3
Total studying exactly two languages

$
2 + 3 = 5
$
$
\text{Probability} = \frac{5}{10} = \frac{1}{2}
$

Question

Bag $A$ and bag $B$ each contain red counters and blue counters only
Stephan picks a counter at random from bag $A$ and Jen picks a counter at random from bag $B.$
The probability that Stephan picks a red counter is $0.4$.
The probability that Stephan and Jen both pick a red counter is $0.25$.
Find the probability that Stephan and Jen both pick a blue counter.

▶️Answer/Explanation

$0.225$

$
P(\text{Red from A}) = 0.4
$
$
P(\text{Red from A and Red from B}) = 0.25
$
Formula for joint probability
$
P(\text{Red from A and Red from B}) = P(\text{Red from A}) \times P(\text{Red from B})
$
$
0.25 = 0.4 \times P(\text{Red from B})
$
$
P(\text{Red from B}) = \frac{0.25}{0.4} = 0.625
$
Probability Stephan picks blue:
$
P(\text{Blue from A}) = 1 – P(\text{Red from A}) = 1 – 0.4 = 0.6
$
$
P(\text{Blue from B}) = 1 – P(\text{Red from B}) = 1 – 0.625 = 0.375
$
Events are independent:
$
P(\text{Blue from A and Blue from B}) = P(\text{Blue from A}) \times P(\text{Blue from B})
$
$
= 0.6 \times 0.375 = 0.225
$

Question

Dan either walks or cycles to school.
The probability that he cycles to school is \(\frac{1}{3}\)
(a) Write down the probability that Dan walks to school.
(b) When Dan cycles to school the probability that he is late is \(\frac{1}{8}\)
When Dan walks to school the probability that he is late is \(\frac{3}{8}\).
Complete the tree diagram.

(c) Calculate the probability that
(i) Dan cycles to school and is late,
(ii) Dan is not late.

Answer/Explanation

Ans:

(a) \(\frac{2}{3}\) oe
(b) their \(\frac{2}{3}, \frac{7}{8}, \frac{5}{8}\) oe
(c) (i) \(\frac{1}{24}\) oe
(ii) \(\frac{17}{24}\) oe

Question



The Venn diagram shows the number of red cars and the number of two-door cars in a car park.
There is a total of 50 cars in the car park.
R = {red cars} and T = {two-door cars}.
(a) A car is chosen at random.
Write down the probability that
(i) it is red and it is a two-door car,
(ii) it is not red and it is a two-door car.
(b) A two-door car is chosen at random.
Write down the probability that it is not red.
(c) Two cars are chosen at random.
Find the probability that they are both red.
(d) On the Venn diagram, shade the region R ∪ T’.(d) On the Venn diagram, shade the region R ∪ T’.

Answer/Explanation

Ans:

(a) (i) \(\frac{5}{50}\) oe
(ii) \(\frac{11}{50}\) oe

(b) \(\frac{11}{50}\) oe

(c) \(\frac{380}{2450}\) oe

(d)

Scroll to Top