# statistics/ probability

• Oct 15th 2008, 02:02 PM
boomshine57th
statistics/ probability
hey guys, could somebody help please? my new teacher does explain anything at all. just gives us slide show printouts. which have calculations without headings or explanation :(
does anybody have a clue how to go about solving this? pretty please?

A manufacturer of electronic components sells 1KW resistors in boxes of
12.A customer requires the components to meet a particular specification, and is happy to accept boxes containing no more than 2which fail to comply. When the manufacturer tests 1000 of his resistors he finds that 89do not meet the specification. If he supplies 200 boxes to the customer, how many can he expect to be rejected?

thank you.
• Oct 15th 2008, 05:59 PM
mr fantastic
Quote:

Originally Posted by boomshine57th
hey guys, could somebody help please? my new teacher does explain anything at all. just gives us slide show printouts. which have calculations without headings or explanation :(
does anybody have a clue how to go about solving this? pretty please?

A manufacturer of electronic components sells 1KW resistors in boxes of
12.A customer requires the components to meet a particular specification, and is happy to accept boxes containing no more than 2which fail to comply. When the manufacturer tests 1000 of his resistors he finds that 89do not meet the specification. If he supplies 200 boxes to the customer, how many can he expect to be rejected?

thank you.

You're probably meant to make some assumptions ......

Let X be the random variable number of defective resistors in a box.

X ~ Binomial(n = 12, p = 89/1000) (there are some assumptions here ......)

Calculate $\displaystyle \Pr(X > 2) = 1 - \Pr(X \leq 2) = \, ....$

Then the expected number of boxes rejected will be 200 Pr(X > 2).