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 #13 : Develop And Compare Probability Models And Find Probabilities Of Events: Ccss.Math.Content.7.Sp.C.7

10% of puppies are born with spots. Of those, 50% have black spots. What is the percentage of puppies who have black spots?

Possible Answers:

Correct answer:

Explanation:

If 10 percent of puppies are born with spots, and of those, 50 percent have black spots, then the total percent of puppies who have spots AND the color of the spots is black can be found by multiplying the two percentages by one another:

0.05 is the equivalent of 5 percent, the correct answer. 

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

Jenny entered a raffle with 9 other participants. The raffle ticket numbers are:

288, 289, 290, 291, 292, 292, 294, 295, 296, 297

Jenny's ticket is 288. The raffler begins to announce the winning ticket. The first digits are 2 and 8. He is about to announce the third digit. 

What are the chances that Jenny won?

Possible Answers:

Correct answer:

Explanation:

There are 10 total participants in the raffle.

288, 289, 290, 291, 292, 292, 294, 295, 296, 297

Only 2 participants have tickets with numbers that beging in 2 and 8.; therefore, Jenny has a 50 percent chance of holding the winning raffle ticket.

The winner is either 288 or 289, leaving Jenny a 50 percent chance. 

Example Question #81 : Statistics & Probability

At a party, there are 5 girls and 5 boys. There is a raffle, and each girl gets twice as many raffle tickets as each boy. Tracy is one of the girls at the party. What is the chance of her winning the raffle if each boy gets 7 raffle tickets?

Possible Answers:

Correct answer:

Explanation:

If each boy gets 7 raffle tickets, that means that each girl gets 14 raffle tickets. 

Therefore, Tracy will have 14 raffle tickets, and the total number of raffle tickets will be equal to 

Thus, Tracy's chance of winning will be equal to:

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

Set  consists of the numbers  and set  consists of the numbers . If a number,  is chosen at random from set , and another number,  is chosen at random from set , what is the probability that  will be equal to an odd number?

Possible Answers:

Correct answer:

Explanation:

Whenever an even number is added to an odd number, the result is odd. Whenever an even number is added to an even number, the result is even. 

Given that all the numbers in set  are even, there is a 100 percent chance of an even number being selected; however in set , one of the three numbers is odd, so there is a one third chance of an odd number being selected. 

Given that the sum of an even number and an odd number is odd, there is a probability of  that the sum of a number randomly selected from set  and from set  wil be an odd number. 

Example Question #82 : Statistics & Probability

Set  consists of the numbers  and set s consists of the numbers . If a number,  is chosen at random from set , and another number,  is chosen at random from set , what is the probability that  will be a negative number?

Possible Answers:

Correct answer:

Explanation:

The only way in which a negative number would be acheived by subtracting  is if  was equal to 2, and any number was selected for

Therefore, the chance of  resulting in a negative number would be equal to the odds of selecting 2 from set . Given that there are four numbers in set , there is a one fourth chance. 

Thus, the correct answer is .

Example Question #83 : Statistics & Probability

Set  consists of the numbers . Set n consists of the numbers . If a number is randomly selected from set  and multiplied by a number randomly selected from set , what is the chance the product will be ?

Possible Answers:

Correct answer:

Explanation:

The only way that a product of  will be acheived is if the number  is selected from set , and the number  is selected from set

There is a one half chance of the number 4 being selected and a one half chance of the number 6 being selected, given that each set contains two numbers. 

Therefore, the probability of both these number being chosen is:

Example Question #81 : Statistics & Probability

If Mark flips a coin and then rolls a die, what are the odds that the coin will be heads and that the die will land on a multiple of 3?

Possible Answers:

Correct answer:

Explanation:

If Mark flips a coin, the chance that it will land on heads is . On a die, there are 2 out of 6 numbers that are a multiple of 3 (3 and 6); therefore, there is a  chance that the dice will be a multiple of 3. 

The probability that the coin will land on heads and that the dice will be a multiple of 3 is:

Example Question #21 : How To Find The Probability Of An Outcome

If Janet rolls a pair of six-sided dice, what is the probability that the dice will come up as snake eyes (meaning that both dice show one dot)?

Possible Answers:

Correct answer:

Explanation:

Given that there are six values that a die may show when rolled, there is a  chance that either dice will show a value of 1. Thus, the chance that both dice will show a value of 1 is equal to , which is equal to .

Thus,  is the correct answer. 

Example Question #84 : Statistics & Probability

If you are picking a random student from a bus with  freshmen,  sophomores,  juniors, and  seniors, what is the probability that you pick a senior?

Possible Answers:

Correct answer:

Explanation:

To find the probability of an event, you divide the possible outcomes of that event by total outcomes.  

The event outcomes would be the  seniors on the bus.  

The total outcomes is the number of students on the bus which is 

.  

So the probability of picking a senior would be 

.

Example Question #21 : Develop And Compare Probability Models And Find Probabilities Of Events: Ccss.Math.Content.7.Sp.C.7

What is the probability of drawing a card that is a spade from a deck of cards?

Possible Answers:

Correct answer:

Explanation:

There are  cards in a deck.  

There are four suits of cards including spades.  

They make up an even amount of the deck each.  

Since there are four of the suits, each represent  of the deck and that is the probability of drawing one.

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