The range of Ervin's scores is 55.
Range is the difference between the largest number and the smallest number.
To find the range of a set of values, first sort the values numerically (smallest to largest). With this set, it would look like this: 138, 142, 155, 165, 172, 193. Lastly, subtract 138 from 193 to find the range. By doing so, you will get 55 as an answer.
I hope this helps!