Question

The mean of a list of 80 numbers is 230. If four numbers 145,156,210, and 255 are added, what is the mean of the list of numbers?

i saw a same question but it wasn't answered correctly, since the answer for this question is 228.17, and i have to show how to get to that answer which i dont know how to do.

Answer 1

Add 145, 156, 210. and 255 then divide by 4. The mean equals 184. 

Answer 2

Step 1: 230 x 80 = 18400
Step 2: add 145, 156, 210, 255 to 18400=19166
Step 3: divide 19166 with 84= 228.17 (answer to nearest 2 decimal points)