Common Core: 7th Grade Math : Statistics & Probability

Study concepts, example questions & explanations for Common Core: 7th Grade Math

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Example Questions

Example Question #561 : Data Analysis And Probability

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

Possible Answers:

\(\displaystyle \frac{1}{13}\)

\(\displaystyle \frac{1}{52}\)

\(\displaystyle \frac{1}{4}\)

\(\displaystyle 4\)

\(\displaystyle 13\)

Correct answer:

\(\displaystyle \frac{1}{4}\)

Explanation:

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

\(\displaystyle \text{probability of event} = \frac{\text{number of ways event can happen}}{\text{total number of possible outcomes}}\)

 

So, given the event of drawing heart, we can calculate the following:

\(\displaystyle \text{number of ways event can happen} = 13\)

because there are 13 ways we can draw a heart:

  • Ace
  • Two
  • Three
  • Four
  • Five
  • Six
  • Seven
  • Eight
  • Nine
  • Ten
  • Jack
  • Queen
  • King

Now, we can calculate the following:

\(\displaystyle \text{total number of possible outcomes} = 52\)

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

 

Knowing this, we can substitute into the formula.  We get

\(\displaystyle \text{probability of drawing a heart} = \frac{13}{52}\)

\(\displaystyle \text{probability of drawing a heart} = \frac{1}{4}\)

 

Therefore, the probability of drawing a heart from a deck of cards is \(\displaystyle \frac{1}{4}\).

Example Question #562 : Data Analysis And Probability

A box contains the following:

  • 9 blue crayons
  • 3 green crayons
  • 4 red crayons
  • 1 yellow crayon

Find the probability of grabbing a red crayon from the box.

Possible Answers:

\(\displaystyle \frac{4}{13}\)

\(\displaystyle 4\)

\(\displaystyle \frac{1}{4}\)

\(\displaystyle \frac{4}{17}\)

\(\displaystyle \frac{1}{17}\)

Correct answer:

\(\displaystyle \frac{4}{17}\)

Explanation:

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

\(\displaystyle \text{probability of event} = \frac{\text{number of ways event can happen}}{\text{total number of possible outcomes}}\)

 

Now, given the event of grabbing a red crayon from the box, we can calculate:

\(\displaystyle \text{number of ways event can happen} = 4\)

because there are 4 red crayons in the box we could grab.

 

We can also calculate:

\(\displaystyle \text{total number of possible outcomes} = 17\)

because there are 17 total crayons we could potentially grab:

  • 9 blue crayons
  • 3 green crayons
  • 4 red crayons
  • 1 yellow crayon

\(\displaystyle 9+3+4+1=17\)

 

So, we get

\(\displaystyle \text{probability of grabbing a red crayon} = \frac{4}{17}\)

 

Therefore, the probability of grabbing a red crayon from the box is \(\displaystyle \frac{4}{17}\).

Example Question #51 : Outcomes

Find the probability that we draw a 5 from a deck of cards.

Possible Answers:

\(\displaystyle \frac{1}{4}\)

\(\displaystyle \frac{1}{13}\)

\(\displaystyle 4\)

\(\displaystyle 1\)

\(\displaystyle \frac{1}{52}\)

Correct answer:

\(\displaystyle \frac{1}{13}\)

Explanation:

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

\(\displaystyle \text{probability of event} = \frac{\text{number of ways event can happen}}{\text{total number of possible outcomes}}\)

 

So, given the event of drawing a 5, we can calculate the following:

\(\displaystyle \text{number of ways event can happen} = 4\)

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

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

Now, we can calculate the following:

\(\displaystyle \text{total number of possible outcomes} = 52\)

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

 

Knowing this, we can substitute into the formula.  We get

\(\displaystyle \text{probability of drawing a 5} = \frac{4}{52}\)

\(\displaystyle \text{probability of drawing a 5} = \frac{2}{26}\)

\(\displaystyle \text{probability of drawing a 5} = \frac{1}{13}\)

 

Therefore, the probability of drawing a 5 from a deck of cards is \(\displaystyle \frac{1}{13}\).

Example Question #61 : Probability

If a class has \(\displaystyle 10\) boys and \(\displaystyle 12\) girls, what is the probability the teacher will call on a boy?

Possible Answers:

\(\displaystyle \frac{1}{10}\)

\(\displaystyle 10\)

\(\displaystyle \frac{10}{12}\)

\(\displaystyle 12\)

\(\displaystyle \frac{5}{11}\)

Correct answer:

\(\displaystyle \frac{5}{11}\)

Explanation:

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

\(\displaystyle \text{probability of an event} = \frac{\text{number of ways event can happen}}{\text{total number of possible outcomes}}\)

 

Now, in the event of calling on a boy in the class, we can determine the number of ways the event can happen:

\(\displaystyle \text{number of ways event can happen} = 10\)

because there are 10 boy students in the class.

 

To find the number of possible outcomes, we get

\(\displaystyle \text{total number of possible outcomes} = 22\)

because there are 22 total students the teacher could potentially call on.

 

Knowing all of this, we can substitute into the formula.  We get

\(\displaystyle \text{probability of calling on a boy} = \frac{10}{22}\)

Reduce:

\(\displaystyle \text{probability of calling on a boy} = \frac{5}{11}\)

 

Therefore, the probability of calling on a boy is \(\displaystyle \frac{5}{11}\).

Example Question #841 : Grade 7

Megan has a bag of marbles containing \(\displaystyle 5\) pink marbles, \(\displaystyle 3\) orange marbles, \(\displaystyle 6\) green marbles, and \(\displaystyle 2\) yellow marbles. What is the probability that Megan will pick a pink marble out of the bag?

Possible Answers:

\(\displaystyle \frac{5}{16}\)

\(\displaystyle \frac{5}{15}\)

\(\displaystyle \frac{4}{16}\)

\(\displaystyle \frac{3}{15}\)

\(\displaystyle \frac{3}{16}\)

Correct answer:

\(\displaystyle \frac{5}{16}\)

Explanation:

In this problem we have a total of \(\displaystyle 16\) marbles. That means that each marble, regardless of color, has a \(\displaystyle \frac{1}{16}\) chance of being picked, as shown in the images below. This image shows equal probability because each marble has a \(\displaystyle \frac{1}{16}\) chance of being drawn, which is equal to the probability of all of the other marbles.

1

Megan wants to know what her probability is of drawing a pink marble out of her bag. Remember, probability is the number of favorable outcomes over the total number of outcomes:

\(\displaystyle \textup{P}=\frac{\textup{favorable outcomes}}{\textup{total outcomes}}\)

For this problem there are \(\displaystyle 5\) pink marbles; therefore, 

\(\displaystyle \textup{P(pink marble)}=\frac{5}{16}\)

 

Example Question #131 : Statistics & Probability

Megan has a bag of marbles containing \(\displaystyle 5\) pink marbles, \(\displaystyle 3\) orange marbles, \(\displaystyle 6\) green marbles, and \(\displaystyle 2\) yellow marbles. What is the probability that Megan will pick an orange marble out of the bag?

Possible Answers:

\(\displaystyle \frac{6}{15}\)

\(\displaystyle \frac{2}{16}\)

\(\displaystyle \frac{3}{16}\)

\(\displaystyle \frac{8}{15}\)

\(\displaystyle \frac{2}{15}\)

Correct answer:

\(\displaystyle \frac{3}{16}\)

Explanation:

In this problem we have a total of \(\displaystyle 16\) marbles. That means that each marble, regardless of color, has a \(\displaystyle \frac{1}{16}\) chance of being picked, as shown in the images below. This image shows equal probability because each marble has a \(\displaystyle \frac{1}{16}\) chance of being drawn, which is equal to the probability of all of the other marbles.

1

Megan wants to know what her probability is of drawing an orange marble out of her bag. Remember, probability is the number of favorable outcomes over the total number of outcomes:

\(\displaystyle \textup{P}=\frac{\textup{favorable outcomes}}{\textup{total outcomes}}\)

For this problem there are \(\displaystyle 3\) orange marbles; therefore, 

\(\displaystyle \textup{P(orange marble)}=\frac{3}{16}\)

Example Question #2 : Develop A Uniform Probability Model By Assigning Equal Probability To All Outcomes: Ccss.Math.Content.7.Sp.C.7a

Megan has a bag of marbles containing \(\displaystyle 5\) pink marbles, \(\displaystyle 3\) orange marbles, \(\displaystyle 6\) green marbles, and \(\displaystyle 2\) yellow marbles. What is the probability that Megan will pick a green marble out of the bag?

 

Possible Answers:

\(\displaystyle \frac{6}{16}\)

\(\displaystyle \frac{8}{16}\)

\(\displaystyle \frac{3}{16}\)

\(\displaystyle \frac{5}{16}\)

\(\displaystyle \frac{2}{16}\)

Correct answer:

\(\displaystyle \frac{6}{16}\)

Explanation:

In this problem we have a total of \(\displaystyle 16\) marbles. That means that each marble, regardless of color, has a \(\displaystyle \frac{1}{16}\) chance of being picked, as shown in the images below. This image shows equal probability because each marble has a \(\displaystyle \frac{1}{16}\) chance of being drawn, which is equal to the probability of all of the other marbles.

1

Megan wants to know what her probability is of drawing a green marble out of her bag. Remember, probability is the number of favorable outcomes over the total number of outcomes:

\(\displaystyle \textup{P}=\frac{\textup{favorable outcomes}}{\textup{total outcomes}}\)

For this problem there are \(\displaystyle 6\) green marbles; therefore, 

\(\displaystyle \textup{P(green marble)}=\frac{6}{16}\)

Example Question #4 : Develop A Uniform Probability Model By Assigning Equal Probability To All Outcomes: Ccss.Math.Content.7.Sp.C.7a

Megan has a bag of marbles containing \(\displaystyle 5\) pink marbles, \(\displaystyle 3\) orange marbles, \(\displaystyle 6\) green marbles, and \(\displaystyle 2\) yellow marbles. What is the probability that Megan will pick a yellow marble out of the bag?

 

Possible Answers:

\(\displaystyle \frac{2}{16}\)

\(\displaystyle \frac{3}{15}\)

\(\displaystyle \frac{2}{15}\)

\(\displaystyle \frac{5}{15}\)

\(\displaystyle \frac{3}{16}\)

Correct answer:

\(\displaystyle \frac{2}{16}\)

Explanation:

In this problem we have a total of \(\displaystyle 16\) marbles. That means that each marble, regardless of color, has a \(\displaystyle \frac{1}{16}\) chance of being picked, as shown in the images below. This image shows equal probability because each marble has a \(\displaystyle \frac{1}{16}\) chance of being drawn, which is equal to the probability of all of the other marbles.

1

Megan wants to know what her probability is of drawing a yellow marble out of her bag. Remember, probability is the number of favorable outcomes over the total number of outcomes:

\(\displaystyle \textup{P}=\frac{\textup{favorable outcomes}}{\textup{total outcomes}}\)

For this problem there are \(\displaystyle 2\) yellow marbles; therefore, 

\(\displaystyle \textup{P(yellow marble)}=\frac{2}{16}\)

Example Question #5 : Develop A Uniform Probability Model By Assigning Equal Probability To All Outcomes: Ccss.Math.Content.7.Sp.C.7a

Samantha has a bag of marbles containing \(\displaystyle 3\) pink marbles, \(\displaystyle 1\) orange marble, \(\displaystyle 2\) red marbles, \(\displaystyle 2\) purple marbles, \(\displaystyle 5\) white marbles, \(\displaystyle 1\) black marble, \(\displaystyle 4\) green marbles, and \(\displaystyle 1\) yellow marble. What is the probability that Samantha will pick a orange marble out of the bag?

 

Possible Answers:

\(\displaystyle \frac{1}{19}\)

\(\displaystyle \frac{1}{18}\)

\(\displaystyle \frac{1}{17}\)

\(\displaystyle \frac{2}{18}\)

\(\displaystyle \frac{2}{17}\)

Correct answer:

\(\displaystyle \frac{1}{19}\)

Explanation:

In this problem we have a total of \(\displaystyle 19\) marbles. That means that each marble, regardless of color, has a \(\displaystyle \frac{1}{19}\) chance of being picked, as shown in the images below. This image shows equal probability because each marble has a \(\displaystyle \frac{1}{19}\) chance of being drawn, which is equal to the probability of all of the other marbles.

1

Samantha wants to know what her probability is of drawing a orange marble out of her bag. Remember, probability is the number of favorable outcomes over the total number of outcomes:

\(\displaystyle \textup{P}=\frac{\textup{favorable outcomes}}{\textup{total outcomes}}\)

For this problem there is \(\displaystyle 1\) orange marble; therefore, 

\(\displaystyle \textup{P(orange marble)}=\frac{1}{19}\)

Example Question #131 : Statistics & Probability

Samantha has a bag of marbles containing \(\displaystyle 3\) pink marbles, \(\displaystyle 1\) orange marble, \(\displaystyle 2\) red marbles, \(\displaystyle 2\) purple marbles, \(\displaystyle 5\) white marbles, \(\displaystyle 1\) black marble, \(\displaystyle 4\) green marbles, and \(\displaystyle 1\) yellow marble. What is the probability that Samantha will pick a pink marble out of the bag?

 

Possible Answers:

\(\displaystyle \frac{2}{19}\)

\(\displaystyle \frac{1}{18}\)

\(\displaystyle \frac{3}{18}\)

\(\displaystyle \frac{1}{19}\)

\(\displaystyle \frac{3}{19}\)

Correct answer:

\(\displaystyle \frac{3}{19}\)

Explanation:

In this problem we have a total of \(\displaystyle 19\) marbles. That means that each marble, regardless of color, has a \(\displaystyle \frac{1}{19}\) chance of being picked, as shown in the images below. This image shows equal probability because each marble has a \(\displaystyle \frac{1}{19}\) chance of being drawn, which is equal to the probability of all of the other marbles.

1

Samantha wants to know what her probability is of drawing a pink marble out of her bag. Remember, probability is the number of favorable outcomes over the total number of outcomes:

\(\displaystyle \textup{P}=\frac{\textup{favorable outcomes}}{\textup{total outcomes}}\)

For this problem there are \(\displaystyle 3\) pink marbles; therefore, 

\(\displaystyle \textup{P(pink marble)}=\frac{3}{19}\)

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