a simple probability question

[maryblue]

say we are having a random drawing and given the following conditions:
the probability of the drawn number greater than 50 is 20%
the probability of the drawn number smaller than -50 is 15%
now what is the probability that the drawn number falls between -50 and 50?

 

[Dr.Peterson]

You've listed three events that are mutually exclusive and exhaustive -- that is, the number has to be in one of the three categories. Do you see the implication of that? (What does the sum of the probabilities have to be?)