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ErinWeeks
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
@jim_thompson5910 .. do you know this ?
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
The 30th percentile is the point where 30% of the data is below that value
but them in order . okay ! i did that part . & what does that mean ?
So if you have say 100 values, then 30% of that (0.3*100 = 30 values) are below the 30th percentile
so in this case we have 10 right .
yes, I'm looking up a percentile formula now, one sec
hmm there are multiple percentile formulas, so it depends on what your book says...do you have your book with you?
yes let me look quick !
my book doesnt have a formula .. it just says percentiles : seperate data sets into 100 equal parts
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
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
so if we're using the correct formula (I hope we are), then the answer is B. 30th percentile = 113; 90th percentile = 200
okay i get that ! (: thank you so much
let me know if it's the right answer or not
yup, you were right :)
thanks for the confirmation
thanks for explaining :)