reasonable standard deviation

this probably isn't the correct place to post... but i'd appreciate any help.

in a limit 5-10 game with 5 average seeing flop and 30% preflop raising (so moderate loose, low-medium aggression), what is a reasonable standard deviation per hour? i was thinking 5 big bets is too low, 10 big bets is too high, so i was going to use 7.5 big bets.

meaning 68% chance up or down 7.5 big bets ($75) in an hour, 95% chance up or down ($150) and 99% chance up or down $225 in an hour....

does that seem low or high to you guys??? just want to run some variance analysis on 2 big bet/hour win rate with a standard deviation??

thanks in advance!