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Help with stats pls!
"The amount of money spent weekly on cleaning, maintenance, and repairs at a large restaurant was observed over a long period of time to be approximately normally distributed, with mean μ = $597 and standard deviation σ = $39.
(a) If $646 is budgeted for next week, what is the probability that the actual costs will exceed the budgeted amount? (Round your answer to four decimal places.)"
Not sure how to set up this problem.. do I find the z score first? And plug in $646 for X? If so, then do I use the "Ncdf" function on my calculator?

Respuesta :

MissPhiladelphia
We are given with 
 μ = $597
σ = $39
X = 646

The z-score is determine using:
z = (X -  μ) / σ
z = (646 - 597) / 39
z = 1.2546

I'm not sure about using the Ncdf function but you can refer to the z-score tables to get the probability for z = 1.2456 which is 0.8944 but this refer to the probability that the actual cost will be less than the budgeted amount. To get the probability that the actual cost will be greater than the budgeted amount we subtract the obtained probability from 1,
1 - 0.8944 = 0.1056

So, the probability is 0.1056 or 10.56%, say 11%.

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