Quiz 4
Statistics 21
Spring 2010
Ibser
For problems 1 and 2, do the following:
a)
Find the expected value and SE for the quantity given.
b)
Use the normal curve to approximate the chance given (don’t worry about whether it’s
appropriate).
c)
Based on the rules given in lecture, say whether you think the normal approximation is
valid, and explain why or why not.
1) Suppose that 200 fair dice are tossed.
a)
Find expected valued and SE for the sum of the 200 rolls.
b)
Find the chance the sum of 200 rolls is at least 715.
c)
Is the normal approximation valid by the rules given in lecture?
Explain why or why not.
2) Suppose you are playing roulette and you place two bets: $1 is put on red and another $1 is put on your
favorite black number. But instead of placing the bets simultaneously, you alternate them. In other words,
you place $1 on red, spin the wheel, and you win or lose money. Then you place another $1 bet on your
favorite black number, spin the wheel, and win or lose. Your net gain or loss is then calculated based on
the outcome from this pair of bets. As a reminder, you have 18/38 chance of landing on red and it pays $1
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 Fall '08
 anderes
 Statistics, Variance, Probability theory, probability density function, Cauchy distribution, Dice, Spins

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