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 Post subject: tricky questions
PostPosted: Wed Dec 30, 2009 10:10 pm 
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Joined: Wed Aug 12, 2009 11:49 pm
Posts: 32
would anyone be kind enough to explain (simply!) how to calculate the following questions:
A water tank is 5 metres long, 4 metres wide and 1.5 metres dee. it is filled using a bucket which holds 1/20 of a cubic metre of water. how many bucketfuls are needed to fill the tank?

2) In the fantasy game creatures have different powers.
5 Elves match 2 wizards
6 deveils match 5 wizards
4 elves match 3 sprites

(a) How many elves match 12 devils? - (I worked this one out)
(B) How many sprites match 8 wizards? - (I have also managed to work this one? :D)
(C)How many devils match 20 elves plus 7 wizards? - (I think I've worked this out.)
(D) How many sprites match 24 devils plus 12 wizards? :roll:
(E) 15 elves plus 12 devils are matched by 8 wizards plus x sprites. what is the value of x? :idea:

A solid letter T is made by glueing together 5 cubes each edge one CM. write down the total surface area of the letter in square CMs. (I have got the answer but can't figure out how arrived at the answer)

A block of metal weighing 180 gms has a volume of 20 cubic CMs. write down the weight in KGs of a block of the same metal which is 1M long, 20CMs wide and 2 CMs thick.


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PostPosted: Wed Dec 30, 2009 10:41 pm 
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Joined: Fri Jul 24, 2009 1:10 pm
Posts: 32
This is how I would attempt the first one

Work out the volume of the pool by multiplying the dimensions of the pool together. The value will be in cubic metres.

Then multiply the volume of the pool by 20 (as the bucket holds 1/20 of a cubic metre)


beebee


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 Post subject:
PostPosted: Wed Dec 30, 2009 11:01 pm 
The volume of the water tank:

5 x 4 x 1.5 = 20 x 1.5 = 30

There are 20/20 in one cubic metre so there are 20 x 30 in tank which is 600 bucketsful.

d) 6 devils = 5 wizards
24 devils = 5 x 4 wizards = 20 wizards

24 devils plus 12 wizards = 32 wizards

2 wizards = 5 elves
so 32 wizards= 5 x 16 elves = 80 elves

4 elves = 3 sprites
80 elves = 3 x 20 sprites = 60 sprites

e) 15 elves + 12 devils = 6 wizards+ 10 wizards = 16 wizards

therefore 16 wizards = 8 wizards + x sprites
x sprites = 8 wizards
8 wizards = 20 elves = 15 sprites (answer to Q.B)

x = 15

The T:

5 at front of T
5 at back of T
3 on top of the T
1 at either end of top, making 2
2 under top of T
2 at each side of T, making 4 altogether
and finally 1 at bottom of T

making 22 altogether. Is that the right answer?



Volume would be 100 x 20 x 2 = 4000 cubic cms

20 = 180 gms
so 4000 (20 x 200) = 180 x 200 gms
= 36000gms
= 36 kgs.

I hope these are right but, if they're not, someone else will probably point out any mistakes I have made.


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 Post subject: Re: tricky questions
PostPosted: Wed Dec 30, 2009 11:08 pm 
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Joined: Fri Jul 24, 2009 1:10 pm
Posts: 32
scooby1 wrote:

2) In the fantasy game creatures have different powers.
5 Elves match 2 wizards
6 deveils match 5 wizards
4 elves match 3 sprites

(D) How many sprites match 24 devils plus 12 wizards? :roll:



original data is

5e=2w
6d=5w
4e=3s

(D)

know that 6 devils=5 wizards
so 24 devils = 20 wizards (multiply both sides by 4)
24 d+12 w =20 w+12 w=32 w

Then convert 32w to elves

5e=2w so 1w= 2 1/2e

32w=32 times 2 1/2e
32w=80 elves

Then convert 80 elves to sprites

4e=3s

multiply both sides by 20

80 elves = 60 sprites


Would you share where these questions are from and what age group/ level they are targeted for?

PS my logic could be wrong - this is just how I would attempt it


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 Post subject:
PostPosted: Thu Dec 31, 2009 1:33 pm 
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Joined: Wed Aug 12, 2009 11:49 pm
Posts: 32
Thanks for your help everyone. I will now attempt to explain to my DS how to wotk them out.

Beebee they are a mixture from Manchester and Stockport Grammar school from past entrance exam papers.


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