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. Concert attendance depends on the weather. There are three possible types of w

ID: 1169369 • Letter: #

Question

. Concert attendance depends on the weather. There are three possible types of weather on the day of the concert: terrible, with probability 20%, mediocre, with probability 60%, and great, with probability 20%. Concert attendance is expected to be 500 people if the weather is terrible, 1000 people if the weather is mediocre, and 2000 people if the weather is great. Let X denote the attendance.

(a) What is the expected attendance, E(X)?

(b) Suppose that each ticket costs $5 and the total cost of giving the concert is fixed and equal $2000. Then, if Y denotes profit from the concert, we have Y = 5X 2000. What is the expected profit?

(c) Find the standard deviation of profit Y .

Explanation / Answer

(a) Expected attendance E(X) = 20%(500) + 60%(1000) +20% (2000) = 100 + 600 + 400 = 1100

(b) Y= 5X-2000

X= 1100 as the expected attendance

Y= 5(1100)-2000 = 3500

(c)

three cases :

Under terrible weather , Y= 5(500)-2000 =500

Under medicore weather, Y = 5(1000)-2000 = 3000

Under great weather , Y=5(2000)-2000 = 8000

Under expected probability = 3500

Use excel function STDEV (RANGE OF VALUES) = STDEV (500,3000,8000,3500) = 3,122.49