0
$\begingroup$

This is going to sound like a dumb question. But what method do I use to add probabilities expressed as decimals . For fractions it is easy add the numerators and denominators then simplify

1/2 + 1/2 = 2/4

In excel if I have 0.5 + 0.5 obviously this equals 1, but when dealing with probabilities I should get back to 0.5

  • 0
    Sorry, this makes no sense. What do you mean by "when dealing with probabilities I should get back to $0.5$"?2012-09-21
  • 0
    What do you exactly mean? Usual fractions add up by the rule $\frac ac+\frac bc=\frac{a+b}c$.2012-09-21
  • 0
    Sorry if I have made myself unclear. If i wish to add together the probabilities 0.5 and 0.5, how do I do it on a calculator or excel ?2012-09-21
  • 3
    What's unclear is the sense in which adding probabilities is different from adding any other kind of number. You must be using the word "adding" to mean something differing from what everyone else means. What exactly do you mean?2012-09-21
  • 0
    What do you mean by "get back to 0.5"? Also, $\frac{1}{2} + \frac{1}{2} \ne \frac{2}{4} $...2012-09-21

3 Answers 3