#### andrew999

##### Member
ok so if house edge is typical .5%, and a spotter would typically maybe play a hand a minute and play for 6 hours that is 600 hands. At \$5 a hand, that means over the course of the whole time, the player would loose \$15. How would one go about finding the standard deviation on this? So that I could figure out how much I needed to cover that.

#### TENNBEAR

##### Well-Known Member
Check the math

andrew999 said:
ok so if house edge is typical .5%, and a spotter would typically maybe play a hand a minute and play for 6 hours that is 600 hands. At \$5 a hand, that means over the course of the whole time, the player would loose \$15. How would one go about finding the standard deviation on this? So that I could figure out how much I needed to cover that.
If a spotter played a hand a minute for 6 hours he would play 360 hands not 600. 360 hands at 5.00 each would total 1800.00 and .05% of that is 90.00 that you would expect to lose. I really do not mean to insult you but you need a calculator Andrew999

#### zengrifter

##### Banned
andrew999 said:
ok so if house edge is typical .5%, and a spotter would typically maybe play a hand a minute and play for 6 hours that is 600 hands. At \$5 a hand, that means over the course of the whole time, the player would loose \$15. How would one go about finding the standard deviation on this? So that I could figure out how much I needed to cover that.
Not much because its a flat bet with minimal variance. BUT, as already pointed out, IF the spotters can count it is NOT optimal for you guys to use this approach - the EV is much higher for each of you to be playing seperately at different tables for the full combined BR. zg

#### gobbledygeek

##### Well-Known Member
TENNBEAR said:
If a spotter played a hand a minute for 6 hours he would play 360 hands not 600. 360 hands at 5.00 each would total 1800.00 and .05% of that is 90.00 that you would expect to lose. I really do not mean to insult you but you need a calculator Andrew999
Shouldn't that be \$1800.00 * 0.005 = \$9.00?

#### TENNBEAR

##### Well-Known Member
gobbledygeek said:
Shouldn't that be \$1800.00 * 0.005 = \$9.00?
Oppps.....Your right, maybe I should be using a calculator

#### Automatic Monkey

##### Banned
andrew999 said:
ok so if house edge is typical .5%, and a spotter would typically maybe play a hand a minute and play for 6 hours that is 600 hands. At \$5 a hand, that means over the course of the whole time, the player would loose \$15. How would one go about finding the standard deviation on this? So that I could figure out how much I needed to cover that.
Uh, you'll have a lot more than that to cover. The spotters have to be paid, and a guy who can count and signal well enough that you can trust him as a spotter isn't going to come cheap. BP tactics are for getting down thousands of dollars per hand. They have no other benefit.

#### dacium

##### Well-Known Member
Its pretty simple. 5\$ per hand and 360 hand with 0.5% house edge.

The expected lose is therefore 360 * 5 * 0.005 = \$9.
This is ONLY TRUE IF YOU SIT DOWN WITH 360 BETS!

If you sit down with less bets you have a chance of dropping your whole bank roll with out reaching the 360 hands, and all the remaining hands are gone begging, they could have won some of your money back.

For example if you sit down with 20 bets, and loose all 20, there is nothing to say you couldn't have ended up 40 bets if you kept going. But you can't because you just blew your whole bank roll.

Basically you have to weigh up the probability of loosing the bank roll with how much you want to loose on average. With 10 bets your average loss will be higher because you are going to bust out occasionly, on 10 bets your average loss will be maybe 20 - 25\$.

I would say 20-30 bets is plenty and average loss will be 18-24\$.

#### Sonny

##### Well-Known Member
andrew999 said:
At \$5 a hand, that means over the course of the whole time, the player would loose \$15. How would one go about finding the standard deviation on this? So that I could figure out how much I needed to cover that.
The variance on one hand of BJ is about 1.33. To calculate the SD for any number of hands use this formula:

SD = Sqrt(1.33 * Number of Hands)

SD = Sqrt(1.33 * 600) = about 28 units

For a 6 hour session that gives us:

EV = -\$15 (as you calculated above)
SD = 28 units = \$140

1 SD range (68%) = -\$155 to \$125
2 SD range (92%) = -\$295 to \$265
3 SD range (99%) = -\$435 to \$405

The ranges above will give you a good idea of what sort of swings to expect on average for a 600 hand session. However, you can’t use the number above to determine your bankroll size because they do not account for losing your money early and having to quit (as dacium mentioned above). For that you will need to use a trip ROR formula like the one in Blackjack Attack.

-Sonny-