part b of this question

Source: Red Swastika

part b of this question

Source: Red Swastika

autolycus

We already have 255 and 160, and the average of 4 numbers is 348. This means we have to top up the first two (i.e. add 93 to 255, add 188 to 160) and add 348 x 2. The remaining 2 numbers thus add up to 93+188+348+348 = 977. The average of the remaining 2 numbers = 977/2 = 488.5.

The largest difference between those numbers is interesting. The smallest 3-digit positive number is 100, so if the last two numbers add up to 977, then one is 100 and the other one is 877. Hence the difference is 777.