Mathematics for IGCSE & O level - Probability (Section 3)
1
Two events are considered independent if:
Answer
(C)
The outcome of the second event is not affected by the outcome of the first.
2
If the probability of an event is 1, what does this indicate?
Answer
(C)
The event is certain.
3
In a survey of 200 people, 120 preferred coffee, 60 preferred tea, and 20 had no preference. What is the probability that a randomly selected person prefers coffee?
Answer
(B)
3/5
4
In a bag, there are 5 green balls, 3 red balls, and 2 yellow balls. If Jai chooses a ball at random, replaces it, and then chooses again, what is the probability that Jai's choices are red and yellow in any order?
Answer
(B)
3/50
5
If the probability of an event is 0.3, what is the probability of its complement (the event not happening)?
Answer
(C)
0.7
6
The sum of all outcomes from a tree diagram is always what?
Answer
(B)
1
7
A jar has 5 blue marbles and 5 red marbles. What is the probability of drawing a blue marble OR a red marble?
Answer
(C)
1
8
A card is drawn at random from a standard deck of 52 playing cards. What is the probability of drawing a King?
Answer
(A)
1/13
9
A spinner has 4 equal sections: red, blue, green, and yellow. What is the probability the spinner lands on blue?
Answer
(A)
1/4
10
What is the probability of rolling a multiple of 3 when you spin a fair spinner numbered from 1 to 6?
Answer
(B)
1/3
11
A fair coin is tossed twice. Which of the following is(are) correct?
Answer
A
B
D
12
If the probability of an event is 1/3, and it is repeated twice, what is the probability that the event happens exactly once?
Answer
(C)
4/9
13
If the probability of winning a game is 0.6, then the probability of losing is:
Answer
(B)
0.4
14
What is the probability of drawing a king or a queen from a standard deck of 52 cards?
Answer
(C)
4/13
15
Which of the following is correct for the total probability for all the outcomes?
Answer
(C)
1
16
A box contains 5 red, 3 blue, and 2 green marbles. If you pick one marble, replace it, and then pick another, what is the probability of picking a red marble and then a blue marble?
Answer
(A)
3/20
17
In a bag, there are 5 green balls, 3 red balls, and 2 yellow balls. If Jai chooses a ball at random, replaces it, and then chooses again, what is the probability that both of Jai's choices are red?
Answer
(B)
3/25
18
A survey of 50 people showed that 30 preferred vanilla ice cream. What is the relative frequency of preferring vanilla?
Answer
(B)
3/5
19
If the probability of an event happening is 0.2, what is the probability of the event *not* happening?
Answer
(C)
0.8
20
What is the probability of drawing a red ball, not replacing it, and then drawing a red ball again, if there are 7 red balls and 3 yellow balls to begin with?
Answer
(C)
7/30
21
A bag contains 6 red balls and 4 black balls. Gita selects a ball, notes its color and replaces it. What is the probability Gita selects two red balls?
Answer
(A)
0.36
22
What is the probability of getting heads when you flip a fair coin?
Answer
(C)
1/2
23
If event A and event B are independent, which formula correctly calculates the probability of both events happening?
Answer
(C)
P(A and B) = P(A) * P(B)
24
A bag contains 10 balls numbered 1 to 10. What is the probability of drawing an even-numbered ball?
Answer
(A)
1/2
25
A die is rolled. What is the probability of getting a number less than 3?
Answer
(B)
1/3
26
Which of the following is a key point for the probability of an event?
Answer
(B)
number of outcomes that give the event/total number of outcomes
27
A bag contains 3 red marbles and 5 blue marbles. What is the probability of choosing a red marble?
Answer
(A)
3/8
28
What is the probability of getting tails when you flip a fair coin?
Answer
(C)
1/2
29
What is the probability of getting a 5 on a single roll of a standard six-sided die?
Answer
(C)
1/6
30
If two events cannot occur at the same time, they are considered:
Answer
(C)
Mutually exclusive
31
A bag contains 4 blue and 6 green marbles. If a marble is selected at random, what is the probability it is *not* blue?
Answer
(C)
1/10
32
The probability of a certain event occurring is 0.1. What is the probability of the event *not* occurring?
Answer
(B)
0.9
33
A box contains 20 marbles: 8 are red, 7 are blue, and 5 are green. What is the probability of selecting a red marble?
Answer
(B)
7/20
34
In the context of probability, the term 'trials' most closely represents:
Answer
(B)
The total number of times an experiment is performed.
35
A die is rolled twice. What is the probability of rolling a 1 on the first roll and a 6 on the second roll?
Answer
(A)
1/36
36
What is the correct formula for P(A and B) if A and B are independent events?
Answer
(C)
P(A) * P(B)
37
Which statement is true about probability values?
Answer
(B)
Probability values always range from 0 to 1, inclusive.
38
A jar contains 2 red marbles, 3 blue marbles, and 5 green marbles. If you pick one marble, what is the probability it is green?
Answer
(B)
1/2
39
A bag contains 7 white balls, 3 black balls. What's the probability of picking a black ball?
Answer
(A)
3/10
40
If the probability of event A is 0.6, what is the probability of the complement of A (not A)?
Answer
(B)
0.4
41
If the probability of a train arriving on time is 0.7, what is the probability that the train is late on three consecutive days, assuming the events are independent?
Answer
(B)
0.027
42
What is the probability of drawing a face card (Jack, Queen, or King) from a standard deck of 52 cards?
Answer
(C)
12/52
43
Consider a six-sided die. Which of the following events are possible when rolling the die?
Answer
A
B
D
44
The probability of an event is 0.7. What are the odds *against* that event happening?
Answer
(A)
3:7
45
A spinner has 3 equal sections: red, blue, and green. What is the probability of landing on blue?
Answer
(B)
1/3
46
What is the probability of getting a tail when you toss a fair coin?
Answer
(C)
1/2
47
If you flip a fair coin, what is the probability of getting heads?
Answer
(C)
1/2
48
If the probability of rolling a prime number on a six-sided die is 1/2, what is the probability of *not* rolling a prime number?
Answer
(C)
1/2
49
What type of diagram is best used to find the probabilities when dealing with dependent events?
Answer
(C)
Tree Diagram
50
What are the odds against rolling a 6 on a standard six-sided die?
