SSAT Middle Level Math : Probability

Study concepts, example questions & explanations for SSAT Middle Level Math

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Example Questions

Example Question #11 : Data Analysis And Probability

A large box contains some balls, each of which is marked with a number; one ball is marked with a "1", two balls are marked with a "2". and so forth up to ten balls with a "10". Two blank balls are also included.

Give the probability that a ball drawn at random will be an even-numbered ball.

Possible Answers:

Correct answer:

Explanation:

The number of balls in the box is 

.

The number of balls with even numbers is 

.

Therefore, if a ball is drawn at random, the probability that an even-numbered ball will be selected is

Example Question #12 : How To Find The Probability Of An Outcome

A large box contains some balls, each of which is marked with a letter of the alphabet. Each vowel is represented by three balls, one red and two blue; each consonant is represented by one ball, which is red. Give the probability that a randomly drawn ball will be blue.

Note: For purposes of this question, "Y" is considered a consonant.

Possible Answers:

Correct answer:

Explanation:

Each of the 26 letters is represented by one red ball; in addition, each of the five vowels is represented by two blue balls for a total of  blue balls. The total number of balls is

.

The probability that a random draw will result in a blue ball being selected is 

.

Example Question #11 : Data Analysis And Probability

A large box contains some balls, each marked with a whole number from "1" to "10". Each odd number is represented by one ball, which is red; each even number is represented by two balls, one red and one green. Five blank yellow balls are then put in the box.

Give the probability that a randomly-drawn ball will be green.

Possible Answers:

Correct answer:

Explanation:

Each whole number from one to ten will be represented by a red ball, for a total of ten balls; each even number will be represented by a green ball, for a total of five balls; there will also be five unmarked yellow balls. The number of balls in the box will be , 5 of which are green, making the probability of a random draw resulting in a green ball

.

Example Question #421 : Ssat Middle Level Quantitative (Math)

A large box contains some balls, each of which is marked with a number; one ball is marked with a "1", two balls are marked with a "2". and so forth up to ten balls with a "10". A blank ball is also included.

Give the probability that a ball drawn at random will NOT be an odd-numbered ball.

Possible Answers:

Correct answer:

Explanation:

The number of balls in the box is 

;

The number of odd-numbered balls is 

.

Therefore, there are  balls that are not marked with an odd number, making the probability that one of these will be drawn .

Example Question #15 : Probability

Find the probability of drawing a 5 from a deck of cards.

Possible Answers:

Correct answer:

Explanation:

To find the probability of an event, we will use the following formula:

 

Now, we will calculate the following:

because there are 4 different ways we can draw a 5 from a deck of cards:

  • 5 of hearts
  • 5 of diamonds
  • 5 of spades
  • 5 of clubs

 

Now, we will calculate the following:

because there are 52 different cards we could potentially draw from a deck. 

 

So, we will substitute.  We get

Therefore, the probability of drawing a 5 from a deck of cards is .

Example Question #13 : How To Find The Probability Of An Outcome

A classroom contains the following:

  • 14 girls
  • 17 boys

Find the probability the teacher calls on a boy.

Possible Answers:

Correct answer:

Explanation:

To find the probability of an event, we will use the following formula:

 

Now, given the event of calling on a boy, we can calculate:

because there are 17 boys in the classroom who can be called on.

 

We can also calculate the following:

because there are 31 total students (14 girls + 17 boys = 31 students) who could potentially be called on.

 

Now, we can substitute.  We get

Therefore, the probability of the teacher calling on a boy is .

Example Question #14 : How To Find The Probability Of An Outcome

All of the clubs are removed from a standard fifty-two-card deck. Two cards are then dealt without replacement. What is the probability that both cards will be red?

Possible Answers:

Correct answer:

Explanation:

Wihtout the clubs, the deck comprises 39 cards, 26 of which are red.

The probability that the first card will be red will be . The probability that the second will then also be red will be . Multiply the probabilities, and result is 

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