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Stat 230 W09 : Gradebook
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Assignment detail for PoWei Chuang in Online Quiz 4:
PoWei Chuang
Login:
pchuang
Email:
pchuang@uwaterloo.ca
Student ID:
20260696
Assignments completed:
22
Assignments active:
0
Question
Grade
1
Cans of soft drinks cost $0.65 in a certain vending machine. What is
the expected value and variance of daily revenue (Y) from the
machine, if X, the number of cans sold per day has E(X) = 140, and
Var(X) = 25?
Your Answer:
E(Y) = 91, Var(Y) = 10.56
Correct Answer:
E(Y) = 91, Var(Y) = 10.56
Comment:
Notice that Y = 0.65*X .Thus:
E(Y) = 0.65*E(X) = 0.65*140 = 91
Var(Y) = (0.65)
2
*Var(X) = 0.4225*25 = 10.56
Instructors Comment:
1.0
2
An insurance company issues a policy on a small boat under the
following conditions: The replacement cost ($14,000) will be paid for
a total loss. If it is not a total loss, but the damage is more than
$9,000, then $8,100 will be paid. Nothing will be paid for damage
costing $9,000 or less and of course nothing is paid out if there is no damage.
The company estimates the probability of the first three events as 0.02, 0.12,
and 0.39 respectively. The amount the company should charge if it wishes to
make a profit of $70 above the expected amount paid out in a year is:
Your Answer:
$1,322
Correct
Answer:
$1,322
Comment:
First calculate the expected payout. Notice that P(no damage) = 1  0.02  0.120.39 =
0.47.
Expected Payout = .0.02(14,000) + 0.12(8,100) + 0.39(0) + 0.47(0) = $1,252, so
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