Question

Help would be appreciated (:
Find the values of the 30th and 90th percentiles of the data. 129, 113, 200, 100, 105, 132, 100, 176, 146, 152
A. 30th percentile = 105; 90th percentile = 200
B. 30th percentile = 113; 90th percentile = 200
C. 30th percentile = 105; 90th percentile = 176
D. 30th percentile = 113; 90th percentile = 176

Answer 1

@jim_thompson5910 .. do you know this ?

Answer 2

First sort the values

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

becomes

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

Answer 3

The 30th percentile is the point where 30% of the data is below that value

Answer 4

but them in order . okay ! i did that part . & what does that mean ?

Answer 5

So if you have say 100 values, then 30% of that (0.3*100 = 30 values) are below the 30th percentile

Answer 6

so in this case we have 10 right .

Answer 7

yes, I'm looking up a percentile formula now, one sec

Answer 8

okay !

Answer 9

hmm there are multiple percentile formulas, so it depends on what your book says...do you have your book with you?

Answer 10

yes let me look quick !

Answer 11

my book doesnt have a formula .. it just says percentiles : seperate data sets into 100 equal parts

Answer 12

well i found one formula to be

n = (P/100)*N + 1/2

So the 30th percentile is at...

n = (30/100)*10 + 1/2

n = 300/100 + 1/2

n = 3 + 1/2

n = 3.5

which rounds to n = 4, so the 4th value (which is 113) is the 30th percentile

Answer 13

If we use the same formula for the 90th percentile, then...


n = (P/100)*N + 1/2

So the 30th percentile is at...

n = (90/100)*10 + 1/2

n = 900/100 + 1/2

n = 9 + 1/2

n = 9.5

which rounds to 10

so the 10th value, which is 200, is the 90th percentile

Answer 14

so if we're using the correct formula (I hope we are), then the answer is

B. 30th percentile = 113; 90th percentile = 200

Answer 15

okay i get that ! (: thank you so much

Answer 16

let me know if it's the right answer or not

Answer 17

yup, you were right :)

Answer 18

thanks for the confirmation

Answer 19

thanks for explaining :)