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Probability, SM-Bank 063

Victoria runs a pet store that sells pure breed dogs.

She has several dogs in the shop from different breeds.
 


 

  1. If one of Victoria's dogs is chosen at random, what is the probability it will be either a labrador or a pug?  (1 mark)

  2. If one of the dogs is chosen at random, what is the probability that the dog is not a bulldog?  (2 marks)
Show Answers Only

a.    \(\dfrac{5}{9}\)

b.    \(\dfrac{5}{6}\)

Show Worked Solution
a.    \(P\text{(Labrador or Pug)}\) \(=\dfrac{\text{Number of Labrador and Pug}}{\text{Total dogs}}\)
    \(=\dfrac{16 + 4}{4+16+6+5+5}\)
    \(=\dfrac{20}{36}=\dfrac{5}{9}\)

 

b.    \(P\text{(Dog not a bulldog)}\) \(=1-P\text{(Dog is a bulldog)}\)
    \(=1-\dfrac{6}{36}\)
    \(=\dfrac{30}{36}=\dfrac{5}{6}\)