Algebra II : Median

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #81 : Median

There are three numbers. Say that one of the numbers represented is . Another number is two times square root of . The last number is one less than . If the sum is three, what is the median of the set?

Possible Answers:

Correct answer:

Explanation:

Let's interpret the problem. One number is . Another is two times square root of  or . The last number is one less than  or . The sum is three which means the equation to set up is: . Let's solve for 

 I want to have the square root on one side and the numbers and variable on the other.

 When  I square both sides, we get a quadratic equation. If I were to square the equation before, I still have a radical to get rid of.           

Remember when foiling, you multiply the numbers/variables that first appear in each binomial, followed by multiplying the outer most numbers/variables, then multiplying the inner most numbers/variables and finally multiplying the last numbers/variables.

 Let's factor out a  to reduce the quadratic.

 If I divide both sides by , I get:

 Remember, we need to find two terms that are factors of the c term that add up to the b term. We have: 

Solve for 

We are not done as the problem asks for median of the set. If we plug in , we have:  or . Once we arrange in increasing order, we have . By checking, the sum is  and the middle number is . Let's check when  is . We have:  or . In increasing order we have . The answer may be 4, HOWEVER, it doesn't satisfy the problem as the sum should be  but instead we have . Therefore the correct answer to this problem is 

Example Question #5 : Median

There is a table of flowers prepared for sale. Twelve flowers are  inches tall, five are  inches tall, and four are  inches tall. What is the median height of these flowers?

Possible Answers:

Correct answer:

Explanation:

The easiest way to do this is first to find the total number of flowers:

Now, the median element is the "middle" term. To find the middle, you can divide 21 by 2:

Since you have an odd number of elements, you unsurprisingly get a fraction. This means that there 10 items to the left of the median and 10 to its right. The 11th term is your median. Now, your group of flowers looks like this:

1-12: 10 inches

13-17: 12 inches

18-21: 15 inches

The 11th item is going to be in that first group, meaning that the median is 10 inches.

If you prefer to write out all of the terms, it will be:

10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 12, 12, 12, 12, 12, 15, 15, 15, 15

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