Introduction To Probability (Copy)
Q1 (Non-Calculator)
What is the probability of rolling a 5 on a fair six-sided die?
Solution:
Favorable outcomes = 1 (only one 5)
Total outcomes = 6
Probability = 1/6
Answer:
1/6
Q2 (Non-Calculator)
A bag contains 3 red balls, 5 blue balls, and 2 green balls. What is the probability of picking a blue ball?
Solution:
Total balls = 3 + 5 + 2 = 10
Favorable outcomes (blue) = 5
Probability = 5/10 = 1/2
Answer:
1/2
Q3 (Non-Calculator)
The probability of an event happening is 0.7. What is the probability that it does not happen?
Solution:
Probability it does not happen = 1 – 0.7 = 0.3
Answer:
0.3
Q4 (Non-Calculator)
A spinner has 8 equal sections numbered 1 to 8. What is the probability of spinning a number greater than 6?
Solution:
Numbers greater than 6 are 7 and 8 (2 outcomes).
Total outcomes = 8
Probability = 2/8 = 1/4
Answer:
1/4
Q5 (Non-Calculator)
In a survey, 60% of people like chocolate. What is the probability, as a decimal, that a person chosen at random does not like chocolate?
Solution:
Probability of liking chocolate = 0.6
Probability of not liking chocolate = 1 – 0.6 = 0.4
Answer:
0.4
Q6 (Calculator)
A card is drawn at random from a deck of 52 cards. What is the probability of drawing a heart?
Solution:
There are 13 hearts in a deck.
Probability = 13/52 = 1/4
Answer:
1/4
Q7 (Calculator)
The probability that a bus is late is 0.2. What is the probability that it is not late?
Solution:
Probability = 1 – 0.2 = 0.8
Answer:
0.8
Q8 (Calculator)
A Venn diagram shows that there are 7 people in set A, 9 in set B, and 4 in both A and B.
How many people are in A only?
Solution:
A only = 7 – 4 = 3
Answer:
3
Q9 (Calculator)
Using the same Venn diagram as Q8, how many people are in A or B?
Solution:
A or B = (A only) + (B only) + (Both)
= (7 – 4) + (9 – 4) + 4
= 3 + 5 + 4
= 12
Answer:
12
Q10 (Calculator)
In a class of 30 students, 18 like maths, 12 like science, and 5 like both.
Find the probability that a randomly chosen student likes either maths or science.
Solution:
Students liking maths or science = 18 + 12 – 5 = 25
Probability = 25/30 = 5/6
Answer:
5/6