Question

In XYZ bistro the sales per day is $1000.00 with the standard deviation of $100. XYZ is open only 6 days a week.

a. what is the chance of having sales more than $1100 in one particular day?

b. what is the chance of having average sales more than $1100 in one particular week?

Answer 1

Part a)

P ( X > 1100 ) = 1 - P ( X < 1100 )
Standardizing the value

Z = ( 1100 - 1000 ) / 100
Z = 1

P ( Z > 1 )
P ( X > 1100 ) = 1 - P ( Z < 1 )
P ( X > 1100 ) = 1 - 0.8413
P ( X > 1100 ) = 0.1587

Part b)

P ( X > 1100 ) = 1 - P ( X < 1100 )
Standardizing the value


Z = 2.45

P ( Z > 2.45 )
P ( X > 1100 ) = 1 - P ( Z < 2.45 )
P ( X > 1100 ) = 1 - 0.9928
P ( X > 1100 ) = 0.0072