The probability that a prize appears in a box of cereal is 0.01. What is the probability that two boxes of cereal contain at least one prize?

Question

The probability that a prize appears in a box of cereal is 0.01.  What is the probability that two boxes of cereal contain at least one prize?

anonymous · Answer

This is a really weird question. O:

anonymous · Answer

apparently this is for business math... lol

anonymous · Answer

what are the options for the problem, hun ?

anonymous · Answer

$$P(A\cup B)=P(A)+P(B)-P(A\cap B)$$

anonymous · Answer

in your case presumably $P(A\cap B)=.01\times .01$

anonymous · Answer

i.e. 
$$.01+.01-.01^2$$

anonymous · Answer

oh okay easy enough, i got .0199

anonymous · Answer

i never know when to use these formulas and when not to

anonymous · Answer

me too

anonymous · Answer

lol always use the formulas that is why they are there
the hardest part is knowing what to use
that comes from interpreting the question correctly

anonymous · Answer

haha what is usually a key word to look for when using this formula? or how did you know?

anonymous · Answer

i know only because i read the question 
there is nothing else to do
but on thing for sure, rarely do you just add probabilities
they can never be bigger than one

anonymous · Answer

ah okay thanks for the tip!

anonymous · Answer

yw