math115
posted by p .
find 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

No.

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? 
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. 
find 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. 
Have 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? 
11 is the median

So what is the rule from your teacher to find the median?

The 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. 
Can you review the steps to see if you followed step 3?
Remember there are ten numbers in all. 
8, 11 add together then divide by 2=9.2

Good, 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. " 
q1=8 q3=14

Perfect!!! 100%
Congratulations, you got it! 
yeah thank you you are totally awesome!!!!! my problem is I have more to be checked not quartiles but others boo me

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