# How do you calculate q1 and q3?

**Steps:**

- Step 1: Put the numbers in order.
- Step 2: Find the median.
- Step 3: Place parentheses around the numbers above and below the median. Not necessary statistically, but it makes Q1 and Q3 easier to spot.
- Step 4: Find Q1 and Q3.
- Step 5: Subtract Q1 from Q3 to find the interquartile range.

A.

### How do you find the first and third quartile?

**To find the quartiles of this data set, use the following steps:**

- Order the data from least to greatest.
- Find the median of the data set and divide the data set into two halves.
- Find the median of the two halves.

#### What are the quartiles in a box and whisker plot?

A five statistical summary can be represented graphically as a**box and whisker plot**(or**box plot**). The first and third**quartiles**are the ends of the**box**, the median is indicated with a vertical line in the interior of the**box**, and the minimum and maximum are the ends of the whiskers (unless an outlier is present).#### How do you find the first and third quartile?

**To find the quartiles of this data set, use the following steps:**- Order the data from least to greatest.
- Find the median of the data set and divide the data set into two halves.
- Find the median of the two halves.

#### What is an interquartile range in math?

The**interquartile range**(**IQR**) is a measure of variability, based on dividing a data set into quartiles. Quartiles divide a rank-ordered data set into four equal parts. The values that divide each part are called the first, second, and third quartiles; and they are denoted by Q1, Q2, and Q3, respectively.

B.

### What does the third quartile tell you?

Mathwords:

**Third Quartile**. For a set of data, a number for which 75% of the data is less than that number. The**third quartile**is the same as the median of the part of the data which is greater than the median. Same as 75th percentile.#### What is the first quartile?

**Lower Quartile**. Q1. For a set of data, a number for which 25% of the data is less than that number. The**first quartile**is the same as the median of the data which are less than the overall median. Same as the 25th percentile.#### What is a box and whisker plot?

A**box and whisker plot**(sometimes called a**boxplot**) is a graph that presents information from a five-number summary. In a**box and whisker plot**: the ends of the**box**are the upper and lower quartiles, so the**box**spans the interquartile range. the median is marked by a vertical line inside the**box**.#### Do quartiles include the median?

Use the**median**to divide the ordered data set into two halves.**Do**not**include the median**into the halves. The lower**quartile**value is the**median**of the lower half of the data. The upper**quartile**value is the**median**of the upper half of the data.

C.

### What is the definition of third quartile?

Q3. For a set of data, a number for which 75% of the data is less than that number. The

**third quartile**is the same as the median of the part of the data which is greater than the median. Same as 75th percentile. See also.#### How do you find the first and third quartile?

The**first quartile**, denoted by Q_{1}, is the median of the lower half of the data set. This means that about 25% of the numbers in the data set lie below Q_{1}and about 75% lie above Q_{1}. The**third quartile**, denoted by Q_{3}, is the median of the upper half of the data set.#### How do you find the lower and upper quartile?

We also know that for a set of n ordered numbers the median is the (n + 1) ÷ 2^{th}value. Similarly, the**lower quartile**divides the bottom half of the data into two halves, and the**upper quartile**also divides the**upper**half of the data into two halves.**Lower quartile**is the (n + 1) ÷ 4^{th}value.#### How do you find the median of a number?

**To find the median number:**- Put all the numbers in numerical order.
- If there is an odd number of results, the median is the middle number.
- If there is an even number of results, the median will be the mean of the two central numbers.

Updated: 22nd September 2018