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Simple Probability Worksheets

Simple Probability Worksheets
  • Page 1
 1.  
A football manufacturer checks 400 footballs and finds that 8 balls are defective. Find the probability that the ball chosen is a defective ball.
a.
2%
b.
3%
c.
20%
d.
41%


Solution:

Number of favorable outcomes = Number of defective balls = 8

Number of possible outcomes = Total number of footballs = 400


= 0.02 x 100 = 2%
P(defective football) = number of defective balls / total number of balls = 8 / 400 = 0.02
[Substitute and simplify.]
[Multiply by 100 to write the decimal in percent form.]

The probability that the ball chosen is a defective ball is 2%.


Correct answer : (1)
 2.  
A basketball player attempts 50 baskets and makes 5. What is the probability of the player making a basket?
a.
0.25
b.
0.1
c.
0.05
d.
0.4


Solution:

Number of favorable outcomes = number of baskets the player makes = 5

Number of possible outcomes = total number of attempts = 50

P(making a basket) = number of baskets / total number of attempts = 5 / 50 = 0.1
[Substitute and simplify.]

The probability of the player making a basket is 0.1.


Correct answer : (2)
 3.  
What are the odds in favor of the coin falling in the shaded region?


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


Solution:

Odds in favor of an event = number of favorable outcomes / number of unfavorable outcomes.

Number of favorable outcomes = 4

Number of unfavorable outcomes = 4

Odds in favor of the coin falling in the shaded region = 4 / 4 = 1 : 1


Correct answer : (3)
 4.  
The probabilities of John or Paula winning a game are shown in the pie chart. Is this a fair game?


a.
Unfair
b.
Fair


Solution:

P (John winning the game) = 0.6

P (Paula winning the game) = 0.4

Each player has different probability of winning the game.

So, the game is unfair game.


Correct answer : (1)
 5.  
Find P(not red), if P(red) is 31%.
a.
31%
b.
19%
c.
69%


Solution:

P (red) = 31% = 0.31
[Convert the percent to decimal by dividing with 100.]

= 1 - 0.31 = 0.69
P (not red) = 1 - P(red)
[Probability of an event not happening = 1 - probability of the event happening.]

So, P(not red) is 69%.
[Convert the decimal to percent by multiplying with 100.]


Correct answer : (4)
 6.  
What is the probability of not getting the newspaper on time, if the probability of getting it on time is 42.4%?
a.
56.1
b.
61.1
c.
59.1
d.
57.6


Solution:

P(on time) = 42.4% = 0.424

P(not on time) = 1 - 0.424 = 0.576
[Subtract]

There is 57.6% chance of not getting the newspaper on time.


Correct answer : (4)
 7.  
The letters C, O, M, P, E, T, I, T, I, O, N are written on cards and put in a hat. One card is selected at random. What is the probability that the card selected bears a consonant?
a.
4 11
b.
5 11
c.
6 11
d.
2 11


Solution:

There are six cards on which consonants ('C', 'M', 'P', 'T', 'N') are written.

Number of favorable outcomes = Number of cards having consonants = 6

Number of possible outcomes = Total number of cards = 11

Probability of drawing a card having consonant = Number of favorable outcomes / number of possible outcomes = 6 / 11


Correct answer : (3)
 8.  
Olga has 8 dollars, 6 nickels, and 10 dimes in her purse. What is the probability of selecting a dime from her purse?
a.
10 11
b.
1 24
c.
5 12
d.
1 14


Solution:

Number of favorable outcomes = Number of dimes = 10

Number of possible outcomes = Total number of coins = 24

= 512
P(dime) = number of dimes / total number of coins = 10 / 24

Probability of selecting a dime is 5 / 12.


Correct answer : (3)
 9.  
20 out of 70 plants had black colored flowers and 50 had violet colored flowers. Find the probability that a plant had violet colored flowers.
a.
1 7
b.
5 7
c.
4 5
d.
None of the above


Solution:

Number of favorable outcomes = Number of plants with violet colored flowers = 50

Number of possible outcomes = Total number of plants = 70

= 57
P(violet) = number of plants with violet colored flowers / total number of plants = 50 / 70
[Simplify.]

The probability that the plant had violet colored flowers is 5 / 7.


Correct answer : (2)
 10.  
A bag contains 15 yellow marbles, 5 black marbles and 15 red marbles. What are the odds in favor of selecting a black marble?
a.
1 30
b.
1 5
c.
1 6
d.
2 7


Solution:

Number of favorable outcomes = Number of black marbles = 5

Number of unfavorable outcomes = Number of marbles excluding black = 30

Odds in favor of an event = Number of favorable outcomesNumber of unfavorable outcomes = 5 / 30 = 1 / 6

Odds in favor of selecting a black marble is 1 / 6 .


Correct answer : (3)

More Simple Probability Worksheets
Basic Probability Worksheet Simple Probability Worksheet
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