Probability exercises solved (easy)

The probability of a given result occurring in a random experiment is expressed through the ratio:

Next we have 10 questionseasy level solved About the subject. After the template we prepare comments that will show you how to perform the calculations.

question 1

If we roll a die, what is the probability of getting a number greater than 4?

a) 2/3
b) 1/4
c) 1/3
d) 3/2

See Answer

Correct answer: c) 1/3

A die has 6 sides with numbers from 1 to 6. Therefore, the number of possibilities at launch is 6.

An event favorable to choosing a number greater than 4 is getting 5 or 6, that is, there are two possibilities.

Therefore, the probability that a number greater than 4 is the result of rolling the die is given for the reason:

question 2

If we flip a coin, what is the probability of the “heads” side facing up?

a) 1/3
b) 1/2
c) 1/4
d) 0

See Answer

Correct answer: b) 1/2

When tossing a coin, there are only two possibilities: flipping a coin. If the event of interest is "head", then the probability of it occurring is given by:

question 3

A restaurant has 13 people: 9 customers and 4 waiters. If we randomly pick a local person, what is the probability of being a customer?

a) 3/13
b) 9/13
c) 6/13
d) 7/13

See Answer

Correct answer: b) 9/13.

If the favorable event is getting a customer, then the number of possibilities is 9.

As the restaurant has a total of 13 people, the probability of randomly choosing a customer is given by:

question 4

If you randomly choose a letter in the alphabet, what is the probability of selecting a vowel?

a) 5/13
b) 7/13
c) 7/26
d) 5/26

See Answer

Correct answer: d) 5/26

The alphabet has 26 letters, of which 5 are vowels. So the probability is:

question 5

If a number from the sequence (2, 3, 5, 7, 11, 13, 17, 19) is randomly chosen, what is the probability of choosing a prime number?

a) 3/8
b) 1
c) 0
d) 5/8

See Answer

Correct answer: b) 1

All 8 numbers in the sequence are prime numbers, that is, they are divisible only by the number 1 and by itself. Therefore, the probability of choosing a prime number in the sequence is:

question 6

If a class consists of 8 female and 7 male students and the teacher chooses randomly a student to go to the board to solve an exercise, what is the probability of being selected a student?

a) 8/15
b) 7/15
c) 11/15
d) 13/15

See Answer

Correct answer: a) 8/15

The total number of students in the class is 15, 8 females and 7 males. As the favorable event is choosing a student, there are 8 possibilities of choice and the probability is given by:

question 7

By randomly choosing a day of the week, what is the probability of choosing a Monday or a Friday?

a) 4/7
b) 1/7
c) 2/7
d) 3/7

See Answer

Correct answer: c) 2/7.

The week is made up of 7 days.

The probability of choosing a Monday is 1/7 and the probability of choosing a Friday is also 1/7.

Therefore, the probability of choosing Monday or Friday is:

question 8

One person went to the bakery to buy bread and yogurt. If the establishment has 30 breads, 5 of which are from the previous day and the others were made on the day, and 20 yoghurts with the date of ineligible validity, of which 1 has already expired, what is the probability of the customer choosing a bread of the day and a yogurt within the validity?

a) 19/24
b) 17/30
c) 14/27
d) 18/29

See Answer

Correct answer: a) 19/24

If the bakery has 30 loaves and 25 are not from the day before, then the probability of choosing a loaf of the day is given by:

If there is an expired yogurt among the 20 units of the bakery, then the probability of choosing a yogurt within the expiration date is:

Therefore, the probability of choosing a bread of the day and a yogurt within the validity period is:

question 9

João has a jar with colored candies. One day he decided to count how many candies of each color were in the container and came up with the numbers:

• 6 red bullets
• 3 green bullets
• 5 white bullets
• 7 yellow bullets

Putting all the candies back in the jar and choosing two candies to eat, what is the probability that John will randomly pick up a red and a yellow candy?

a) 4/19
b) 3/27
c) 1/23
d) 2/21

See Answer

Answer: d) 2/21

The total number of bullets in the pot is: 6+3+5+7 = 21

The probability of catching a red bullet is given by:

The probability of choosing a yellow candy is:

Therefore, the probability of choosing a red and a yellow candy is:

question 10

What is the probability of choosing a card from the deck and that card is not an ace?

a) 12/17
b) 12/13
c) 14/13
d) 12/11

See Answer

Answer: b) 12/13

A deck consists of 52 cards, of which 4 are ace, one in each suit.

So the probability of picking an ace is .

The probability of not picking an ace is:

Get more knowledge with the contents:

• Concept and calculation of probability
• conditional probability
• Probability Exercises
• combinatorial analysis
• Exercises on combinatorial analysis
• Permutation