If there are 21 values in a data set in order from smallest to largest, what is the third quartile of the data set?

I do not know the values of the numbers so I cannot give u a direct answer.
1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21

Q1 (quartile 1) = take the 5th and 6th number and divide it by 2
Q2 (quartile 2, median) = the 11th number
Q3 (quartile 3) = take the 16th and 17th number and divide it by 2

(1 - x) represent the percent, in decimal form, of the initial price.