Percentiles numbers, between, however, question, recently

simeezee

hi guys, hoping someone can clarify -- I thought that to calculate percentiles, you used the formula (n+1)*(y/100) where y is the percentile eg 50 for 50th percentile etc.

however i recently saw a question that seemed to contradict this.

so, to clarify. if you have 10 numbers in ascending order, is the 50th percentile:

a) the fifth biggest number

or

b) (10+1)*(50/100) ie 5.5, or the point that's halfway between number 5 and number 6 in your list.

this is such a simple topic so i can't understand why there seem to be contradictory ways of solving it. thanks much.