The median of first 10 prime numbers is
The first ten prime no's are :
2, 3, 5, 7, 11, 13, 17, 23, 29, 31
Clearly, the data is in ascending order. and
No of terms, n = 10
We know that, if even no of terms or observations are given, then the median of data is mean of the values of 
term and 
term. Where n is no of terms.
In this case, n = 10
i.e. median of above data is mean of 5th and 6th term
⇒ median 
⇒ median = 12
17