High School Math : Understanding Mean, Median, and Mode

Study concepts, example questions & explanations for High School Math

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Example Questions

Example Question #11 : Basic Statistics

\(\displaystyle 14\) is the ____________ of the following dataset below.

\(\displaystyle \{20, 12, 17, 14, 12\}\)

Possible Answers:

range

median

mean

mode

Correct answer:

median

Explanation:

Reorder the numerals in the set, from least to greatest.

\(\displaystyle \{12, 12, 14, 17, 20\}\)

The number in the middle is the median. \(\displaystyle \{12, 12, \mathbf{14}, 17, 20\}\)

The most frequent numeral is the mode. \(\displaystyle \{\mathbf{12}, \mathbf{12}, 14, 17, 20\}\)

The mean is the sum of the numerals divided by the number of data points.

\(\displaystyle \frac{12+12+14+17+20}{5}=15\)

The mean is 15.

The range is the difference between the maximum and the minimum.

\(\displaystyle 20-12=8\)

The range is 8.

Example Question #1 : Understanding Mean, Median, And Mode

For the following data set:

\(\displaystyle 2,\; 5,\; 9,\; 3,\; 7,\; 12,\; 15,\; \; 10,\; 9\)

Which is the smallest?

Possible Answers:

Range

Mean

Median

Mode

None of the answers

Correct answer:

Mean

Explanation:

Put the data in order from smallest to largest and then calculate each stastic:  mean, mode, median, range

\(\displaystyle 2,\;3,\;5,\;7,\;9,\;9,\;10,\;12,\;15\)

\(\displaystyle Range = Max - Min\) or \(\displaystyle 15-2=13\)

Mode is the most often repeated number or \(\displaystyle 9\)

Median is the number in the middle or \(\displaystyle 9\)

Mean is the sum of the data divided by the number of data points or \(\displaystyle \frac{\sum x}{n}= \frac{72}{9}=8\)

Example Question #1 : Understanding Mean, Median, And Mode

\(\displaystyle 1,1,2,3,6,8,10,11,12,15, 30\)

\(\displaystyle \textup{What is the median of the above number set?}\)

Possible Answers:

\(\displaystyle 8\)

\(\displaystyle 11\)

\(\displaystyle 9\)

\(\displaystyle 1\)

\(\displaystyle 15\)

Correct answer:

\(\displaystyle 8\)

Explanation:

\(\displaystyle \textup{As the numbers are already listed in increasing order, the median is simply}\)

\(\displaystyle \textup{the one in the middle. In this case 8 is the 6th term counted from either side..}\)

Example Question #1 : Data Properties

Find the median of the following number series:

3, 6, 27, 19, 8, 11, 30, 42, 7, 39

Possible Answers:

19

19.2

30

15

11

Correct answer:

15

Explanation:

The first step to finding the median is always to put the numbers in the proper order:

3, 6, 7, 8, 11, 19, 27, 30, 39, 42

When we have an even amount of numbers, we find the average (or mean) of the middle two to get the median:

11 + 19 = 30/2 = 15

Example Question #2 : Data Properties

With a standard deck of playing cards, what is the probability of picking one red card followed by one black card, without replacement?

Possible Answers:

\(\displaystyle \frac{1}{26}\)

\(\displaystyle \frac{17}{52}\)

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

\(\displaystyle \frac{17}{25}\)

\(\displaystyle \frac{13}{51}\)

Correct answer:

\(\displaystyle \frac{13}{51}\)

Explanation:

In a standard deck of playing cards we have:

\(\displaystyle 26\; red+26\; black=52\; cards\)

So the probability of picking the first card red is \(\displaystyle \frac{26}{52}=\frac{1}{2}\).

Then the probability of picking the second card black is \(\displaystyle \frac{26}{51}\) because this is without replacement.

They are independent events so the probabilities get multiplied together to give \(\displaystyle \frac{13}{51}\).

Example Question #2 : Understanding Mean, Median, And Mode

Which statement is true concerning the following data set:

\(\displaystyle 2,5,9,3,4,7,3,8,11,15,10\)

Possible Answers:

\(\displaystyle mode+median> range\)

\(\displaystyle mode+mean = median\)

\(\displaystyle mean=median\)

\(\displaystyle range - mode = mean\)

\(\displaystyle mode+mean = median\)

\(\displaystyle mode> mean\)

Correct answer:

\(\displaystyle mean=median\)

Explanation:

First, put the data in order, smallest to largest:

\(\displaystyle 2,3,3,4,5,7,8,9,10,11,15\)

\(\displaystyle mean = \frac{\sum x}{n}=\frac{77}{11}=7\)

\(\displaystyle mode=3\)

\(\displaystyle median = 7\)

\(\displaystyle range=max-min=15-2=13\)

Note, the mode is the number most often repeated in the data set and the median is the middle number.

So \(\displaystyle mean=median\) is the only true statement.

 

Example Question #2 : Understanding Mean, Median, And Mode

Alice recorded the outside temperature at noon each day for one week. These were the results.

Monday: 78

Tuesday: 85

Wednesday: 82

Thursday: 84

Friday: 82

Saturday: 79

Sunday: 80

What was the mean temperature for the week?

Possible Answers:

\(\displaystyle 81\)

\(\displaystyle 84\)

\(\displaystyle 81.43\)

\(\displaystyle 83.72\)

\(\displaystyle 82\)

Correct answer:

\(\displaystyle 81.43\)

Explanation:

The mean is calculated by adding all the values in a group, then dividing the sum by the total number in the group. 

 

\(\displaystyle 78+85+82+84+82+79+80=570\)

 

\(\displaystyle 570/7=81.43\)

Example Question #1 : Understanding Mean, Median, And Mode

Alice recorded the outside temperature at noon each day for one week. These were the results.

Monday: 78

Tuesday: 85

Wednesday: 82

Thursday: 84

Friday: 82

Saturday: 79

Sunday: 80

What is the mode of the temperatures?

Possible Answers:

\(\displaystyle 82\)

\(\displaystyle 84.5\)

\(\displaystyle 80\)

\(\displaystyle 85\)

\(\displaystyle 81.4\)

Correct answer:

\(\displaystyle 82\)

Explanation:

The mode is the number that appears most frequently in a series of numbers.  First, organize the numbers in order from least to greatest.  Then, identify the value that is repeated most frequently.

 

\(\displaystyle 78, 79, 80, 82, 82, 84, 85\)

Example Question #2 : Understanding Mean, Median, And Mode

Alice recorded the outside temperature at noon each day for one week. These were the results.

Monday: 78

Tuesday: 85

Wednesday: 82

Thursday: 84

Friday: 82

Saturday: 79

Sunday: 80

What is the median temperature?

Possible Answers:

\(\displaystyle 570\)

\(\displaystyle 82\)

\(\displaystyle 83\)

\(\displaystyle 7\)

\(\displaystyle 81.4\)

Correct answer:

\(\displaystyle 82\)

Explanation:

The median is determined by ordering the values in the group from least to greatest and identifying the value directly in the middle.  For instance, if five numbers are ordered from least to greatest, the third is the median. 

 

\(\displaystyle 78, 79, 80, 82, 82, 84, 85\)

Example Question #2 : Understanding Mean, Median, And Mode

What is the probability of rolling an odd sum less than seven when rolling two standard six-sided dice?

Possible Answers:

\(\displaystyle \frac{1}{3}\)

\(\displaystyle \frac{5}{18}\)

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

\(\displaystyle \frac{1}{6}\)

\(\displaystyle \frac{1}{2}\)

Correct answer:

\(\displaystyle \frac{1}{6}\)

Explanation:

The sample space for rolling two six-sided dice is \(\displaystyle 36\).

The odd numbers less than seven are one, three, and five.

The smallest sum you can get with two dice is \(\displaystyle 2\).

sum of \(\displaystyle 3:\; \; 1,2\; \;\; 2,1\)

sum of \(\displaystyle 5:\; 1,4\; \; \; 2,3\; \; \; 3,2\; \; \; 4,1\)

\(\displaystyle P(1)+P(3)+P(5)=0+\frac{2}{36}+\frac{4}{36}=\frac{6}{36}=\frac{1}{6}\)

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