defective. a) If 10% of all such bulbs are defective, what’s the probability that exactly 8 out of 100 bulbs are defective? Use the binomial formula.
Flash bulbs manufactured by a certain company are sometimes defective.
a) If 10% of all such bulbs are defective, what’s the
100 bulbs are defective? Use the binomial formula.
b) Imagine taking a sample of 100 bulbs, counting the number of defective ones, and
calculating ˆp (e.g. 7 defective bulbs means ˆp =7/100 = 0.07). There are lots of differentpˆ’s you might get, so let’s think about the sampling distribution of ˆp’s.
• What value is this sampling distribution centered around? I’m looking for a
number, not a symbol.
• What’s the standard error of this sampling distribution?
• Is this sampling distribution approximately normal? How do we know?
c) Approximate the probability that at least 8 of the 100 bulbs are defective.Hint: You’ll want to sketch the sampling distribution that you described in part (b)
and see where this sample falls on there. Then use the Z-table.
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