SOLUTION: Suppose the string of Christmas lights you just bought has twenty-four bulbs wired in series. Suppose that each bulb has a 97% chance of “working” the first time current is a

Let's first calculate the probability that the string of lights WILL work.
Then we'll subtract that from 1 to find the probability that it will FAIL
to work.

For the string of lights to WORK, that means:

the 1st bulb works AND the 2nd bulb works AND the 3rd bulb works AND ∙∙∙ the
24th bulb works.

So that's (0.97)(0.97)∙∙∙(0.97) to 24 factors or (0.97)24 = 0.4814172219 
or a string will work about 48% of the time.  So the other 52% of the time a
string will fail. 

We calculate 1 - 0.4814172219 and get 0.5185827781 or a probability of
51.85827781% of the time that a string will fail, and then round that off
to as many decimal places as your teacher says to round it.

Edwin