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Simple Probability Worksheet

Simple Probability Worksheet
  • Page 1
 1.  
What is the probability of selecting one blue ball from a box containing 6 blue balls?
a.
2
b.
3
c.
1
d.
4


Solution:

The number of possible outcomes is 6.
[Since there are 6 blue balls in the box.]

The number of favorable outcomes is 6.
[Since there are 6 blue balls in the box.]

Probability(event) = (Number of favorable outcomes)(Number of possible outcomes)
[Formula]

P(blue ball) = 66 = 1
[Substitute the values.]

The probability of selecting a blue ball is 1.


Correct answer : (3)
 2.  
When a number cube is rolled, what is the probability of rolling a 4?
a.
1 2
b.
2 3
c.
1 6
d.
1 3


Solution:

The numbers on a cube are 1, 2, 3, 4, 5, and 6.

Total number of outcomes = 6

Number of favorable outcomes = 1
[The only favorable outcome is 4.]

Probability(event) = Number of favorable outcomesNumber of possible outcomes
[Formula.]

P(rolling 4) = 1 / 6
[Substitute the values.]

The probability of rolling a 4 when a number cube is rolled is 1 / 6.


Correct answer : (3)
 3.  
A coin is tossed once. What is the probability of getting a head?
a.
1 5
b.
1 3
c.
1 2
d.
1 4


Solution:

Total number of possible outcomes = 2
[Head and Tail.]

Number of favorable outcomes = 1.
[1 Head is the only favorable outcome from the possible outcomes.]

P(event) = Number of favorable outcomesNumber of possible outcomes
[Formula.]

P(heads) = 12
[Substitute the values.]

Probability of getting a head is 1 / 2.


Correct answer : (3)
 4.  
What is the probability of choosing an even number from the numbers 1, 5, 7, 9, 6, 8?
a.
1 4
b.
1 3
c.
1
d.
1 2


Solution:

Total number of outcomes is 6.

Number of favorable outcomes is 2.
[Only 6 and 8 are even numbers.]

Probability(event) = Number of favorable outcomesNumber of possible outcomes
[Formula.]

P(even) = 26
[Substitute the values.]

= 13
[Simplify.]

The probability of getting an even number is 1 / 3.


Correct answer : (2)
 5.  
What is the probability of getting an odd number when a dice is rolled?

a.
1 3
b.
1 2
c.
1 5
d.
1 4


Solution:

The possible numbers are 1, 2, 3, 4, 5 and 6.

Total number of outcomes when a dice is rolled is 6.

Number of favorable outcomes is 3.
[1, 3, 5 are the odd numbers.]

Probability(event) = (Number of favorable outcomes)(Number of possible outcomes)
[Formula.]

P(getting an odd number) = 3 / 6
[Substitute the values.]

= 1 / 2
[Divide the numerator and the denominator by 3.]

Probability of getting an odd number when a dice is rolled is 1 / 2.


Correct answer : (2)
 6.  
What is the probability of selecting a number, which is a multiple of 2, from the numbers 5 to 24?
a.
7 20
b.
3 20
c.
1 2
d.
1 24


Solution:

Total number of outcomes for selecting a number from 5 to 24 is 20.

Multiples of 2 from 5 to 24 are 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24.

So, the number of favorable outcomes is 10.

Probability(event) = Number of favorable outcomesNumber of possible outcomes
[Formula.]

P(multiple of 2) = 1020
[Substitute the values.]

Probability of selecting even numbers from numbers 5 to 24 is 1 / 2.


Correct answer : (3)
 7.  
What is the probability of selecting a yellow marble from a box containing 5 yellow and 4 violet marbles?
a.
1
b.
4 9
c.
1 9
d.
5 9


Solution:

Total number of possible outcomes = 5 + 4 = 9

Number of favorable outcomes is 5.
[Since there are 5 yellow marbles.]

Probability(event) = Number of favorable outcomesNumber of possible outcomes
[Formula.]

P(yellow marble) = 59
[Substitute the values.]

Probability of selecting a yellow marble from 9 marbles is 5 / 9.


Correct answer : (4)
 8.  
What is the probability of selecting a vowel from the word "CHRISTOPHER"?
a.
4 11
b.
3 11
c.
1 11
d.
2 11


Solution:

Total number of letters in the word "CHRISTOPHER" is 11.

So, the number of possible outcomes is 11.

Number of favorable outcomes is 3.
[I, O, E are the only vowels present in the word.]

Probability(event) = (Number of favorable outcomes)(Number of possible outcomes)
[Formula]

P(vowels) = 311
[Substitute the values.]

Probability of selecting a vowel from the word "CHRISTOPHER" is 3 / 11.


Correct answer : (2)
 9.  
What is the probability of drawing a nickel from a bag containing 9 dimes and 5 nickels?
a.
1 14
b.
5 14
c.
9 5
d.
9 14


Solution:

Number of possible outcomes = 9 + 5 = 14

Number of favorable outcomes = 5
[Since there are 5 nickels.]

Probability(event) = (Number of favorable outcomes)(Number of possible outcomes)
[Formula]

P(drawing a nickel) = 5 / 14
[Substitute the values.]

The probability of drawing a nickel from a bag containing 9 dimes and 5 nickels is 5 / 14.


Correct answer : (2)
 10.  
One letter is chosen at random from the word "MISSISSIPPI". What is the probability of choosing the letter S?
a.
2 11
b.
3 11
c.
1 11
d.
4 11


Solution:

Total number of letters in the word "MISSISSIPPI" is 11.

So, number of possible outcomes is 11.


Number of favorable outcomes is 4.
[There are 4 S's in the word "MISSISSIPPI".]

Probability(event) = (Number of favorable outcomes)(Number of possible outcomes)
[Formula]

P(Letter S) = 411
[Substitute the values.]

Probability of picking S from the word "MISSISSIPPI" is 4 / 11.


Correct answer : (4)

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