PSAT Math : Statistics

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #21 : Probability

The Sugar Shak has a "make your own sundae" bar. You can choose one of three ice creams (strawberry, chocolate, or vanilla), one of three sauces (strawberry, carmel, or chocolate), and one of four toppings (peanuts, whipped cream, cherry, or M&Ms). How many different sundaes can be made?

Possible Answers:

10

36

25

40

18

Correct answer:

36

Explanation:

We have three choices for ice cream, three choices for sauces, and four choices for toppings.  Each selection is an independent event, so the choices are multiplied together: 3 * 3 * 4 = 36.

Example Question #22 : Probability

A bag contains two white marbles, five green marbles, and three red marbles. What is the probability of picking two red marbles if replacement is not allowed?

Possible Answers:

6/7

2/3

1/5

3/5

1/15

Correct answer:

1/15

Explanation:

Probability is a number between 0 (will not happen) and 1 (will definitely happen).  Probability is generally a fraction where the numerator is the total of what you want to happen and the denominator is the total count.

Total ways to choose two red marbles:  3 * 2 = 6

Total ways to choose two marbles:  10 * 9 = 90

Therefore, the probability of choosing two red marbles is 6/90 or 1/15

Example Question #3111 : Sat Mathematics

What is the probability of choosing three hearts in three draws from a standard deck of playing cards, if replacement of cards is not allowed?

Possible Answers:

13/750

21/500

57/1000

43/250

11/850

Correct answer:

11/850

Explanation:

The standard deck of cards has 52 cards: 13 cards in 4 suits.

Ways to choose three hearts:  13 * 12 * 11 = 1716

Ways to choose three cards:  52 * 51 * 50 = 132600

Probability is a number between 0 and 1 that is defines as the total ways of what you want ÷ by the total ways

The resulting simplified fraction is 11/850

Example Question #145 : How To Find The Probability Of An Outcome

A lottery is being run at a high school to allocate parking spots.   The school has 200 seniors, 300 juniors, 350 sophomores, and 450 freshmen.  Each eligible senior will have their name entereted into the lottery twice, with all other eligible students' names being entered once.  Only juniors and seniors will be eligible for parking spots.  If there are 150 parking spots, what is the probability that any given junior will receive a spot?

Possible Answers:

1/100

2/7

3/14

3/5

4/9

Correct answer:

3/14

Explanation:

Find the probabilty a junior's name will be pulled for a single lottery trial.  Then calculate the probability given 150 lottery trials.

(200 seniors * 2 entries each) + 300 juniors = 700 entries

For any single junior then, the odds are 1/700 for a single lottery trial.

For 150 trials, a junior will have (1/700 * 150 trials) = 150/700, which simplifies to

3/14 

Example Question #22 : Probability

A number between 1 and 15 is selected at random.  What are the odds the number selected is a multiple of 6?

Possible Answers:

2/15

The answer is not listed

1/7

3/15

3/7

Correct answer:

2/15

Explanation:

In the set of 1 to 15, two numbers, 6 and 12, are multiples of 6. That means there are two chances out of 15 to select a multiple of 6.

2/15

Example Question #31 : How To Find The Probability Of An Outcome

A big box of crayons contains a total of 120 crayons. 

The box is composed of 3 colors; red, blue, and orange. 30 of the crayons are red, 40 of the crayons are blue and the rest are orange. If one picks a crayon randomly from the box, what is the probability that it will be orange? 

Possible Answers:

7/12

3/7 

2/7 

5/12

1/3 

Correct answer:

5/12

Explanation:

To solve the problem one must calculate that there are 50 orange crayons in the box. So 50/120 are orange. If we simplify that fraction by 10 we get 5/12.

Example Question #22 : How To Find The Probability Of An Outcome

A skydiver is trying to determine the probability of landing within the target of a grass field. If the field measures 1000 meters by 500 meters and the target area measures 50 meters by 50 meters, what is the probability of the skydiver landing in the target area?

Possible Answers:

3/400

5/200

3/200

1/200

1/100

Correct answer:

1/200

Explanation:

Find the area of the entire field and the target area. The fraction of the field that is the target area is equal to the probability of the skydiver hitting the target area. For example, if the field were 100 m3 and the target area was 100 m3 than the probability would be 1. If the field were 100 m3 and the target area was 50 m3 than the probability would be 0.5 and so on.

(50 * 50)/(1000 * 500) = 5/1000 = 1/200

Example Question #191 : Data Analysis

If a container holds 4 red balls, 3 yellow balls, and 2 blue balls, what are the odds of picking out both of the blue balls without replacement?

Possible Answers:

2/9

1/8

1/36

1/72

1/6

Correct answer:

1/36

Explanation:

You take the probability of the first outcome times the probability of the second, so (2/9) * (1/8) = 2/72 = 1/36

Example Question #3113 : Sat Mathematics

Let R = {1, 3, 4, 12}, and let Q = {2, 6, 8, 24}. If one number is randomly selected from R, and another is randomly selected from Q, what is the probability that the product of those two randomly chosen numbers will belong to Q?

Possible Answers:

1/4

9/16

1/2

5/8

5/16

Correct answer:

9/16

Explanation:

First, let's consider all of the pairs that could be chosen from R and Q. There are sixteen possibilities:

1 and 2; 1 and 6; 1 and 8; 1 and 24; 3 and 2; 3 and 6; 3 and 8; 3 and 24; 4 and 2; 4 and 6; 4 and 8; 4 and 24; 12 and 2; 12 and 6; 12 and 8; 12 and 24.

Now, we need to find the product of each of these pairs, and then determine whether or not they belong to Q. The products of all of the possible pairs would be as follows:

1(2) = 2, which belongs to Q

1(6) = 6, which belongs to Q

1(8) = 8, which belongs to Q

1(24) = 24, which belongs to Q

3(2) = 6, which belongs to Q

3(6) = 18, which doesn't belong to Q

3(8) = 24, which belongs to Q

3(24) = 72, which doesn't belong

4(2) = 8, which belongs to Q

4(6) = 24, which belongs to Q

4(8) = 32, which doesn't belong

4(24) = 96, which doesn't belong

12(2) = 24, which belongs to Q

12(6) = 72, which doesn't belong

12(8) = 96, which doesn't belong

12(24) = 288, which doesn't belong

Thus, of our sixteen possible combinations, there are 9 which, when multiplied, give a number that belongs to Q. Because probability is the number of successful events out of the total number of events, the probability is 9/16.

The answer is 9/16.

Example Question #31 : How To Find The Probability Of An Outcome

1) If John does not have freckles, he is not Tim's sibling.

2) If Jake does not have freckles, he is Tim's sibling.

3) If Suzy is not Tim's sibling, she will not have freckles.

4) All of the other answers are false.

All of Tim's siblings have freckles. Which of the above statements must be true?

Possible Answers:

3) If Suzy is not Tim's sibling, she will not have freckles.

4) All of the other answers are false.

1) If John does not have freckles, he is not Tim's sibling.

2) If Jake does not have freckles, he is Tim's sibling.

Correct answer:

1) If John does not have freckles, he is not Tim's sibling.

Explanation:

Only John's statement must be true. Suzy could have freckles and not be Tim's sibling and if Jake doesn't have freckles then he is not Tim's sibling.

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