Track the changing counts when an object is not replaced.
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First lesson in this subject: Count equally likely outcomes
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A bag contains 5 red counters and 3 blue counters. Each draw chooses uniformly from the counters still in the bag. Draws are without replacement.
The first red chance is 5/8. If that counter is red, 4 red and 3 blue remain, so the next red chance is 4/7. Both the favorable count and the total change.
You are reading the opening. Members read every lesson and guide in full. A free account reads the first lesson in each subject in full.
You are reading the opening. Your free account reads the first lesson in each subject in full. Members read every lesson and guide in full.
First lesson in this subject: Count equally likely outcomes
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Practice · Work through restricted sample spaces, linked selections and conditional events. Explore the counts behind each answer.
Book · Count outcomes, update chances with new information, and compare decisions through worked examples.
Previous lesson · Use natural counts to choose the right conditional denominator.
Next lesson · Explain why the same empty door can lead to different odds.
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