our class was given a set of data where we were tasked to find the first percentile using interpolation. The given set of data is as follows (in billion of dollars):
18, 18, 18, 18, 19, 20, 20, 20, 21, 22, 22, 23, 24, 26, 27, 32, 33, 49, 52, 56
We were taught to use the formula k(n+1)/100 where K = kth percentile, which in this case is 1, and where n = no. of data which is 20, and solving this gives you the percentile's location. But, when I solved it, it gives me 0.21, which isn't a whole number, so how do I solve this?
Much thanks in advance, R.
You got 0.21. We count it to nearest whole number.
So, we count up one number. So, we get 18.
You can look Similar example here finding 3rd percentile.