A level maths help needed!!!

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Juliakinga
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#1
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#1
A car is available in a number of models.
30% are three door hatch backs, 55% are 5 door hatchbacks and the remainder are convertibles.
Of the three door hatcbacks: 60% have a 1.1 litre engine, 15% have a 1.4 litre engine and 25% have a diesel engine.
Corresponding figures for five door hatchbacks: 15%, 55% and 30%
For convertibles: 5%, 85% and 10%

Find the probability that two of these cars (chosen at random) have the same engine.

I don't understand how to find this, even though I have drawn a tree diagram.
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Theghostwrighter
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#2
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#2
(Original post by Juliakinga)
A car is available in a number of models.
30% are three door hatch backs, 55% are 5 door hatchbacks and the remainder are convertibles.
Of the three door hatcbacks: 60% have a 1.1 litre engine, 15% have a 1.4 litre engine and 25% have a diesel engine.
Corresponding figures for five door hatchbacks: 15%, 55% and 30%
For convertibles: 5%, 85% and 10%

Find the probability that two of these cars (chosen at random) have the same engine.

I don't understand how to find this, even though I have drawn a tree diagram.
Initially work out the probability of a three-door with a 1.1 litre then a 1.4 litre then deal then repeat for the two other types of car. To help convert the percentages into fraction to get easier numbers. Then extend the tree diagram to factor in the choice of a second car but remember you only need to work out the probability of the same engine so there is still three options
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Juliakinga
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#3
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#3
(Original post by Theghostwrighter)
Initially work out the probability of a three-door with a 1.1 litre then a 1.4 litre then deal then repeat for the two other types of car. To help convert the percentages into fraction to get easier numbers. Then extend the tree diagram to factor in the choice of a second car but remember you only need to work out the probability of the same engine so there is still three options
thank you!
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