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junior college 1 | H1 Maths
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kim Yeon Jae
Kim Yeon Jae

junior college 1 chevron_right H1 Maths chevron_right Singapore

29(b) please

Date Posted: 1 month ago
Views: 7

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Eric Nicholas K
Eric Nicholas K's answer
3654 answers (Tutor Details)
1st
Q29a, Q29b

All 20 models are vehicle models. For this part it does not matter what type of vehicle is selected.
J
J
1 month ago
If 29b) is interpreted differently, the 3 vehicles are of different categories

The probability would be 7C1 x 8C1 x 5C1
= 7 x 8 x 5
= 280
Eric Nicholas K
Eric Nicholas K
1 month ago
But that would be taking 1 model of each type of vehicle.

The question seems to suggest that any three different models of vehicles will do.

If the question says “three different types of vehicles” instead of “three different models of vehicles”, then 7C1 x 8C1 x 5C1 = 280 will be good.
J
J
1 month ago
It all depends on how the setter does his phrasing.

One way would be to take 'vehicle models' as a umbrella/general term and therefore choosing 3 different ones results in 20C3.

But then since all of them are distinct models anyway, it could have just been phrased as 'how many ways are there to choose 3 different models' without the word 'vehicle'.


So the word 'vehicle' here could be taken to mean that each vehicle is of a different category. I.e different vehicle model in the sense that car models, motorcycle model and minibus models are different



But then again, the phrasing for d) could be used to argue that if c) was asking for 3 different vehicle types, it would have been phrased like d) and be something like :

'how many ways are there to choose 3 vehicles with 1 car, 1 motorcycle and 1 minibus model?'


I would say the first interpretation is more likely, but then given what has been posted on this app (if you recall yesterday's question), the purpose is to show another interpretation for exposure
J
J
1 month ago
Anyway to add on, the word 'model' is used to describe within a brand of a type/kind of vehicle. Eg. tesla model 3, model X, model S etc.

So the term 'vehicle model' isn't very appropriate since it's combining one general term (vehicle) with one specific term(model)
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Eric Nicholas K
Eric Nicholas K's answer
3654 answers (Tutor Details)
Q29c

Here the type of vehicle matters so we have to do them separately.