1. Probability
S1.2 Core Plenary
Baljit has a new remote control for his TV.
It takes three batteries. He puts the batteries in randomly (without looking).
What is the probability that he gets them in the correct way round like this?
Challenge: What would this probability be if Baljit’s remote took four batteries instead of three?
Preamble
The task involves dealing with a ‘real-life’ probability situation. The most capable pupils could be asked about any inherent assumption behind the ‘simple’ probability calculation.
Possible content Listing all the possible outcomes of an event in a logical manner using a convenient notation.
Resources
None.
Solution/Notes
Using arrows is one way to list all the battery configurations.
For example           
So the probability of getting the correct configuration () is .
In the 4-battery case there 16 possible configurations, giving a probability of .
Original Material © Cambridge University Press 2009
Original Material © Cambridge University Press 2009