Originally Posted by

**turtle27** This is my homework question:

There is an 81% chance a new Nogo car will have no defects. A dealer has just received 5 new Nogos. What is the probability that 2 or less of the cars have no defects?

**I worked the problem and got 61% is that right? If not, can you show me the right way to do it? I'm supposed to use the nCr formula.**

Here's the second question: again using the nCr method.

18) A shipment of D-cell batteries left the Pretty Good Battery Company before the quality inspectors checked them. Unfortunately, 10 out of every 100 of these batteries was no good. Ferdinand bough 4 of these batteries from a local 24 hourstore.

(a) What is the probability that exactly one of the batteries that he bought was

no good? **I computed this answer to be 42%. is this right?**

(b) What is the probability that at most one of the batteries that he bought was

no good? **I computed this and got 1.25%. I think that is very wrong...**

Thanks for all the help!