Question

Find the values of the 30th and 90th percentiles of the data. Please show your work.
129, 113, 200, 100, 105, 132, 100, 176, 146, 152

Answer 1

100, 100, 105, 113, 129, 132, 146, 152, 176, 200

Answer 2

ok it looks like you have ordered the data from least to greatest

Answer 3

and that is the first step

Answer 4

ok good, but i have no idea where to go after that

Answer 5

the second step is trying to figure out what number to use for the 30th percentile
which number in the data gives us 30 percent of the elements of the data below it

Answer 6

you have 10 elements

Answer 7

you want to multiply this number by 30%

Answer 8

this will tell us which number in the data is going to have 30% of the elements below it

Answer 9

10*30%=3

Answer 10

so 105?

Answer 11

100, 100, 105, 113, 129, 132, 146, 152, 176, 200

so 105 is the third number
the only thing is there are two elements below it and 2 elements of a 10 piece data set is not 30% of the data

Answer 12

so we find the average of 105 and the next number in the data and use that as our 30 percentile number

Answer 13

so
105+113=218
218/2=109

Answer 14

ok that looks great

Answer 15

YAY!.....now what?

Answer 16

do similar thing for finding 90th percentile number

Answer 17

the number you choose you want 90% of the elements laying below it (instead of 30% like we did with the 30th percentile number)

Answer 18

so
10*90%=9
#9=176, #10=200
176+200=376
376/2=188

Answer 19

sorry the notification thingy didn't work

Answer 20

its fine

Answer 21

that looks great to me

Answer 22

ok thanks!

Answer 23

http://www.dummies.com/how-to/content/how-to-calculate-percentiles-in-statistics.html
another very followable example here if you want to read

Answer 24

anyways great job

Answer 25

thanks, thank you for explaining it to me