A spinner has four sectors: red 180°, blue 90°, yellow 60° and green 30°…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A spinner has four sectors: red , blue , yellow and green . Find the probability of red and of blue, as decimals. Why is the answer for red not ?
Need a reminder? The key ideaShow
With equally likely outcomes, . Every probability lies from (impossible) to (sure). The probabilities of all the elementary events add up to . For unequal sectors, a sector's chance is its angle out of .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Red. .
Step 2. Blue. .
Step 3. Why not one in four. The four colours are not equally likely, because their sectors are not the same size. Counting one colour of four only works for equal sectors.
Answer: and .
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