Step by step
The question
Question: find the probability of win, when the odds for win are 4 to 6.
The odds for are the outcomes for, to the outcomes against.
1 For and against
So 4 outcomes are for win.
And 6 are against.
2 Add for all
All the outcomes: for plus against.
4 plus 6 is 10.
3 Write the fraction
The probability is for over all: 4/10.
Careful!
The bottom is all the outcomes, for plus against: 10.
Not only the 6 against.
4 Simplify
Both 4 and 10 can be divided by 2.
That makes it simpler.
So it is 2/5.
5 Check
Let's check by going back.
2 out of 5 are for, and 3 against.
The odds for: 2 to 3.
And 4 to 6 simplifies to the same.
So the answer is right!
Let's look back.
First: for and against.
Then: add for all.
Then: write the fraction.
Then: simplify.
Last: check.