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.

Question part points submissions used suppose that 100 lottery tickets are given out in sequence to the first 100 guests to arrive at a party. of these 100 tickets, only 12 are winning tickets. the generalized pigeonhole principle guarantees that there must be a streak of at least l losing tickets in a row. find l.

How much dextrose 70% must be mixed with dextrose 5% to prepare 1,000 ml of dextrose 20%?

Solve for x and y a x= 13.3 y= 16.7 b x= 23.3 y= 12.5 c x= 7.5 y= 16.7 d x=7.5 y= 12.5