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## Homework Statement

There are 100 light bulbs in a box. 20 are 40 watt, the rest are 60 watt.

If we randomly choose 10 bulbs, what is the probability that there will be exactly 2 40-watt bulbs?

What is the probability that in a random sample of 10 bulbs there will be at least 1 40-watt bulb?

and then i am also having trouble with this one

75% of a certain part is supplied by vendor A and 25% by vendor B. Vendor A's defect rate is 0.01 and vendor B's defect rate is 0.03.

If a part is from vendor A, what is the probability it is defective?

What is the probability that a randomly chosen part will be defective and from vendor A?

What is the probability that a randomly chosen part will be non-defective and from Vendor B?

## The Attempt at a Solution

I think that these are nCr problems but I am very confused by these problems, if someone could explain them to me that would be amazing, thank you so much.