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Posted by **p** on Friday, October 16, 2009 at 11:37am.

3,4,8,8,8,11,13,14,15,18 is it q1=3 and q3 = 18

- math115 -
**Ms. Sue**, Friday, October 16, 2009 at 12:05pmNo.

- math115 -
**MathMate**, Friday, October 16, 2009 at 12:07pmThere are different formulas for finding the quartiles.

Can you dig out the one used by your teacher and post it here so we can help you check if you did it correctly?

- math115 -
**p**, Friday, October 16, 2009 at 3:51pmRewrite the given data set in ascending order.

Step 2 Find the median.

Step 3 Make a list of only those numbers (in order) that are to the left of the

median.

Step 4 Find the median of the list created in Step 3; this is the first quartile Q1.

Step 5 Repeat steps 3 and 4 with those numbers that are to the right of the

median; this gives the third quartile Q3.

- math115 -
**p**, Friday, October 16, 2009 at 3:54pmfind the first and third quartile in the set of numbers

3,4,8,8,8,11,13,14,15,18 is it q1=3 and q3 = 18

math115 - Ms. Sue, Friday, October 16, 2009 at 12:05pm

No.

math115 - MathMate, Friday, October 16, 2009 at 12:07pm

There are different formulas for finding the quartiles.

Can you dig out the one used by your teacher and post it here so we can help you check if you did it correctly?

math115 - p, Friday, October 16, 2009 at 3:51pm

Rewrite the given data set in ascending order.

Step 2 Find the median.

Step 3 Make a list of only those numbers (in order) that are to the left of the

median.

Step 4 Find the median of the list created in Step 3; this is the first quartile Q1.

Step 5 Repeat steps 3 and 4 with those numbers that are to the right of the

median; this gives the third quartile Q3.

- math115 -
**MathMate**, Friday, October 16, 2009 at 4:04pmHave you done step 2? What is the median of the 10 numbers?

Now can you find out how to find the median, according to your teacher, so that we can follow that step by step?

- math115 -
**p**, Friday, October 16, 2009 at 4:08pm11 is the median

- math115 -
**MathMate**, Friday, October 16, 2009 at 4:15pmSo what is the rule from your teacher to find the median?

- math115 -
**p**, Friday, October 16, 2009 at 4:17pmThe median is the number for which there are as many instances that are above

that number as there are instances below it. To find the median, follow these

steps:

Step 1 Rewrite the numbers in order from smallest to largest.

Step 2 Count from both ends to find the number in the middle.

Step 3 If there are two numbers in the middle, add them together and find

their mean.

- math115 -
**MathMate**, Friday, October 16, 2009 at 4:19pmCan you review the steps to see if you followed step 3?

Remember there are ten numbers in all.

- math115 -
**p**, Friday, October 16, 2009 at 4:25pm8, 11 add together then divide by 2=9.2

- math115 -
**MathMate**, Friday, October 16, 2009 at 4:31pmGood, but I suppose you meant 9.5 which is (8+11)/2.

Perfect!

Now that you have found the median correctly according to your teacher's instructions, we can continue to find the quartiles. The number 9.5 can be thought of as between the fifth and the sixth number, or the 5.5th number. Can you now do step 3 and 4 for the quartiles. Tell me what you found.

"Step 3 Make a list of only those numbers (in order) that are to the left of the median.

Step 4 Find the median of the list created in Step 3; this is the first quartile Q1. "

- math115 -
**p**, Friday, October 16, 2009 at 4:33pmq1=8 q3=14

- math115 -
**MathMate**, Friday, October 16, 2009 at 4:44pmPerfect!!! 100%

Congratulations, you got it!

- math115 -
**p**, Friday, October 16, 2009 at 4:47pmyeah thank you you are totally awesome!!!!! my problem is I have more to be checked not quartiles but others boo me

- math115 -
**MathMate**, Friday, October 16, 2009 at 5:08pmYou're welcome!

You work well and did well following your teacher's instructions.