Luckily, we are provided with a data set that is already in numerical order: 

.

To find the range, we subtract the lowest value from the highest, 

.

To find the mean, we add all of the data pieces and divide by the number of data pieces, 

.

To find the mode, we search for numbers tha appear more than once. Since none of these data values appear more than once, we have no mode. 

The course grade average is calculated by using Sally's three test scores and final exam. student must score at least an average of ; therefore we can write the following:

Given that the average is calculated using three test scores and a final weighted as two regular tests, we can write the following equation. 

Let's use these equations to construct an inequality where we will substitute in our known values and let a variable, , equal the final score needed to earn an a  or above.

Sally needs to at least score a  on the final to score  or above.

In order to find out how much money Alex earned during the fourth hour, we need to understand how to find the mean of a set of numbers (also known as the 'average'). To find the mean of any set of numbers, we first add together all of the numbers in the set to find a total sum, and then we divide this sum by the amount of numbers that are in the set:

Let's look at the information given to us in this problem. We know several things:

- The mean amount of money that Alex earned each hour was 

- Alex worked for a total of 

- The amount of money earned for three out of four of the hours (; ; )

We DON'T know how much money Alex earned during the 4th hour, but we can figure it out by plugging in what we know into the equation for finding the mean of a set, as follows:

For "Mean", we plug in the mean amount that Alex earned (which was ). For "sum of all numbers" we plug in the amount that Alex earned for every hour, and add them all together. Since we only know how much money Alex earned for three out of the four hours, we'll use  as a placeholder for the fourth hour. For "amount of numbers in set", we plug in , since that is the total number of hours that Alex worked.

Now, all we need to do is solve for . We'll do this by first adding together all of the numbers in the numerator of our fraction:

Next, we multiply both sides of our equation by , in order to get rid of our fraction:

Finally, subtract  from both side to get  by itself:

So,  is our answer. 

0, 1, one fourth, twenty five percent, , 16, 25

First we will list the numbers from least to greatest:

0, one fourth, twenty five percent, , 1, 16, 25

 The median is the middle number, or , which can also be expressed as

The median, by definition, is the middle number in a set of numbers which, in this case, is 21.  The mean is the average of the set of numbers, which is 20 for this set.

Regardless of the value of , these elements are in ascending order. There are five elements, so the third-highest element is the median, as there will be two elements greater than this one and two elements less than this one. This number is .

The problem is asking for the median of the ages. The answer is easiest to see if you look at the extreme case of all the unkown people being younger than the known people. If the 3 unknown people were 10 years old, the line would be 10, 10, 10, 14, 16, 16, 17, making 14 the median. With 4 people older than 14, there is no way to have a median below 14.

The median of 99 natural numbers is the number that falls in the  place when ordered. Among the first 99 natural numbers, this is 50.

First put your set in numerical order, from smallest to largest

Median refers to the number in the middle, so if you count in from both sides the middle number of the set is