How is this done in Excel?

For the Stochastic Model, use a Normal Distribution Curve, with the Mean being the Average Weekly Sales, and the weekly Standard Deviation being $5,000. That is, all weekly sales will fall between the Average - 3 Standard Deviation and Average + 3 Standard Deviation. For example, if average weekly says is 100,000 then the 99% of weekly sales would fall between 85,000 and 115,000. Use the RANDBETWEEN function in excel to get this random sales number. To get discount per week, once again use a RAND () function to get a 0 (no loyalty card) or a 1 (loyalty card) and calculate the random discount based on loyalty card info. Calculate new sales, and difference in profit margin (The cost of the Loyalty Program). Now, since this is a stochastic model, you need to run it three times (use the F9 function to re-calculate spreadsheet). Make sure you tabulate each iteration so you can get a MEAN of the Cost of Loyalty Program.

Supermarket		Calendar Week	Average Sales in $ ('000s)
Average Weekly Sales over 5 years		1	$350.00
Normal Distribution		2	$360.00
Standard Deviation	5	3	$350.00
3Sigma Mininmum 44.5% of Sales	15	4	$380.00
3Sigma Maximum 44.5% of Sales	15	5	$370.00
Probability of Loyalty Card	0.63	6	$380.00
Discount Loyalty Card	0.04	7	$350.00
		8	$380.00
		9	$360.00
		10	$330.00
		11	$350.00
		12	$390.00
		13	$390.00
		14	$380.00
		15	$350.00
		16	$340.00
		17	$380.00
		18	$400.00
		19	$360.00
		20	$510.00
		21	$500.00
		22	$380.00
		23	$390.00
		24	$370.00
		25	$360.00
		26	$370.00
		27	$550.00
		28	$480.00
		29	$380.00
		30	$350.00
		31	$330.00
		32	$340.00
		33	$380.00
		34	$360.00
		35	$390.00
		36	$340.00
		37	$370.00
		38	$350.00
		39	$370.00
		40	$330.00
		41	$340.00
		42	$320.00
		43	$380.00
		44	$360.00
		45	$480.00
		46	$510.00
		47	$550.00
		48	$550.00
		49	$400.00
		50	$500.00
		51	$480.00
		52	$550.00