Question

What is the probability of either event occurring when you spina spinner with the numbers 1 through 4 which are all evenlyrepresented?Event A: Spinning an odd numberEvent B: Spinning a 4

Answer 1

We are given an experiment, and we are asked about the probability that either event happens. Therefore, we use the addition rule of probability, which states that if A and B are two events in a probability experiment the probability that either one of the events to happen is:

`P(A\text{ }or\text{ }B)=P(A)+P(B)\text{ - }P(A\text{ }and\text{ }B)`

Therefore, in our specific case, we have that the probability of A is 1/2, since we have 2 odd numbers out of possible 4 outcomes. The probability of B is 1/4, since we have a number 4 out of 4 possible outcomes. The probability of A and B is 0, because obtaining a 4 and an odd number are two mutually exclusive events. Therefore we have that our probability simply is the sum of our two probabilities:

`P(A\text{ }or\text{ }B)=(1)/(2)+(1)/(4)=(2)/(4)+(1)/(4)=(3)/(4)`

Therefore, our answer is 3/4