Advanced EV Calculation via simulation

Hello All,

I love slots and have recently started to take advantage of bonus offers from casinos. I've completed all offers with a positive EV. I have been using a very simplistic version of an EV calculation:

EV = Bonus - (Wagering * House Edge)

This has served me well, however now I want to start on offers that the above formula provides negative EV. After a lot of research I found the BonusChum software (see link below). It simulates how users perform on different slots and provides and average EV rate. What I believe is going on now is the following:

I don't like just using software without knowing the ins and outs of the calculations being performed. Looking at just the simplistic situation of a cashable bonus with the following info added:

Deposit £100
Bonus £100
Wager: x50 Bonus (£5,000)
Low Variance Slot
House Edge: 2.98%
Bet Size: £1
Universes: 100,000
RUN

Returned Values:
EV: £36.20
Bust Rate: 81.89%
Avg Wagering: £2133.22

My basic calculation would have determined an EV of (£100 - (£5000 * 2.98%) = -£49

I am really keen to understand how the above values are determined.

- How is the SD (standard deviation) calculated for slots (low, med, high, v.high) ?
- By selecting Low Var & house edge of 2.95%, BonusChum displays an SD of 4.8209 how is this calculated?
- How is the paytable (probability & payout) calculated? - is this coming from the SD graph, where expected outcomes are within 3 SD of the mean?


I've looked through so many forum posts without being able to find out how it works.
/forum/questions-and-answers/math/22690-slot-machine-standard-deviation/

bonuschum software like:
/software/bonuschum/