Question

Suppose spin a spinner with eight equal sectors, numbered 1 to 8. What is the probability of spinning a 3 or an 8?

Answer 1

$\frac{2}{8} = \frac{1}{4}$

Answer 2

Given, in the spinner 8 equal sectors, numbered 1 to 8.

So total numbers = 8.

Let, the probability of spinning a 3 is P(Three) and spinning an 8 is P(Eight).

Now we know that, probability of an event E is

P(E) = (number of outcomes in the event)/ (total number of possible outcomes).

So here number of outcomes for spinning a 3 is 1 and we have got total outcomes = 8.

So P(Three) = $\frac{1}{8}$

Similarly, P(Eight) = $\frac{1}{8}$

Probability of spinning a 3 or an 8 = P(Three) + P(Eight)

= $\frac{1}{8} + \frac{1}{8}$

As the denominator is same we can add the numerator.

= $\frac{(1+1)}{8}$

= $\frac{2}{8}$

Now we have to simplify the fraction by dividing the numerator and denominator by a common factor of them.

The common factor of 2 and 8 is 2. So by dividing them we will get,

= $\frac{1}{4}$

We have got the required answer.

The probability of spinning a 3 or an 8 is $\frac{1}{4}$