questions appeared

here are some questions appeared on the competition:

Quote:

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19. Which of the following sets of coordinates indicates a function?

a. (1,2)(1,3)(1,0)
b. (2,0)(9,10)(1000/500,3)
c. (2,1)(-2,12)(3,-2)
d. (1.6,8)(16,8)(1 3/5,8)
e. None of the above

20. What is the least whole number for which 3x>10?

a. 3 1/3
b. 3
c. 4
d. 30
e. None of the above

23. How many natural numbers are between (5)^1/2 and (10)^1/2?

a. 5
b. 6
c. 4
d. 1
e. None of the above

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Can anyone solve at least one? I'm not sure if I got it right on these.

Well, #20 is obviously C

:)

Quote:

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Originally posted by thinktank2


d.(1.6,8)(16,8)(1 3/5,8) --- This is a many to one function, where all elements in the domain are mapped to 8

So, I would bet on d

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1.6 is equal to 1 3/5, so the right answer must be c :)

Quote:

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Originally posted by riis


1.6 is equal to 1 3/5, so the right answer must be c :)

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http://www.vbforums.com/images/icons/icon14.gif :)

Sorry, I am going to call myself a careless person for putting the http://www.vbforums.com/images/icons/icon14.gif
without checking what you said...

you said
(1.6,8)(16,8)(1 3/5,8)

is equivalent to

(1.6,8)(16,8)(1.6,8) since 1 3/5 is actually 1.6

But it still is a many to one function because a single element in domain is mapped to a unique element in range.

If it is given like ...
(1.6,8)(16,8)(1.6,2)

then 1.6 is mapped to two different values. So it is not a function.

But in (1.6,8)(16,8)(1.6,8)

1.6 is mapped to only one value 8
16 is mapped to only one value 8

So this is a valid many to one function.

This supports my earlier asssumption. I would bet on d.

My fault, didn't notice that :)

Yes, this is a function where f(x) = 8.

I'm not sure about c, 'cos this could probably also be a function.

Which competition was this from??? I'm doing one soon, but not multiple choice.