order set...{160,165,170,240,240,450}
The "mean" is the arithmetic average of the elements...
mean=(160+165+170+240+240+450)/6=237.5
The "median" if the set has an odd number of terms is the middle term, if the set has an even number of terms, it is the average of the middle two terms.
In this case the number of elements is even and the middle two terms are 170 and 240 so:
median=(170+240)/2=205
The "mode" is the term which appears the most in the set, so in this case:
mode=240