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PostPosted: Tue Aug 20, 2013 3:28 pm 
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Joined: Tue Aug 20, 2013 3:20 pm
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Hi All - Hope you can help with this VR question, as I believe both answers are correct.

15(32)2 14(30)2 12( ?) 4

My daughter gets two answers, 28 or 50, depending on how she works it out.
For 50 = she does 15x2 = 30 +2. 14x2=28+ 2 and then 12 x 4 = 48 +2 = 50, so, she multiplying the numbers outside the brackets and then adding 2.

For 28 = she does 15x2 = 30 +2. 14x2=28+ 2 and then 12 x 2 = 24 +4 = 28 and here she is multiplying by 2 and adding the other number outside the bracket.

Can someone please advise which is the correct method.

Thanks !


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PostPosted: Tue Aug 20, 2013 4:58 pm 
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Joined: Sun Sep 23, 2012 11:51 pm
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tbaby21 wrote:
Hi All - Hope you can help with this VR question, as I believe both answers are correct.

15(32)2 14(30)2 12( ?) 4

My daughter gets two answers, 28 or 50, depending on how she works it out.
For 50 = she does 15x2 = 30 +2. 14x2=28+ 2 and then 12 x 4 = 48 +2 = 50, so, she multiplying the numbers outside the brackets and then adding 2.

For 28 = she does 15x2 = 30 +2. 14x2=28+ 2 and then 12 x 2 = 24 +4 = 28 and here she is multiplying by 2 and adding the other number outside the bracket.

Can someone please advise which is the correct method.

Thanks !


Hi, I don't understand why she is doing "12 x 2 = 24 + 4"
She should only use the information given in the question, otherwise she would have to make illogical assumptions. I have taught my ds to only go by the information contained in the question, so the answer would have to be 50
HTH
x


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PostPosted: Tue Aug 20, 2013 5:06 pm 
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We believe it's also 50, but the answer in the booklet is 28, which is why we are confused.


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PostPosted: Tue Aug 20, 2013 5:11 pm 
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How very odd, which test and question number is it, if you don't mind me asking?


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PostPosted: Tue Aug 20, 2013 5:18 pm 
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Actually I would go the other way and say the answer was 28.

It just seems much simpler and more consistent to say the rule is "double the number on the left and add the number on the right" - which gives the answer 28.

To come up with 50 you're saying the rule is "times the left number by the right number and then add 2" but where does the adding of the number 2 come from? If it is because that's the number on the right in the two examples then it doesn't work with the test question unless you make an assumption to add 2 as the number on the right here is 4. I can see how you could find the answer to be either - but the "double and add" rule just seems a bit neater somehow...maybe someone better than me can give guidance...

(sorry if this comment makes no sense - toddler nagging to type distracting me...x)


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PostPosted: Tue Aug 20, 2013 5:22 pm 
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semb wrote:
Actually I would go the other way and say the answer was 28.

It just seems much simpler and more consistent to say the rule is "double the number on the left and add the number on the right" - which gives the answer 28.

To come up with 50 you're saying the rule is "times the left number by the right number and then add 2" but where does the adding of the number 2 come from? If it is because that's the number on the right in the two examples then it doesn't work with the test question unless you make an assumption to add 2 as the number on the right here is 4. I can see how you could find the answer to be either - but the "double and add" rule just seems a bit neater somehow...maybe someone better than me can give guidance...

(sorry if this comment makes no sense - toddler nagging to type distracting me...x)


That makes absolute sense when you put it that way :)
I just can't find the question, and have looked through both sets of Bright Sparks papers..


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PostPosted: Tue Aug 20, 2013 5:26 pm 
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Joined: Mon Jan 30, 2006 4:07 pm
Posts: 2660
Copy and paste from one of my old posts...

This one gets my children in a tizz every year

There are 3 answers, but luckily only one is on the answer sheet, the question is not be a good candidate for standard form.

15 (32) 2 14 (30) 2 12 ( ) 4

Method 1

15 x 2 = 30
add number on the right
30 + 2 = 32

14 x 2 = 28
add number on the right
28 + 2 = 30

12 x 4 = 48
add the number on the right
48 + 4= 52

Method 2


15 x 2 = 30
add 2
30 + 2 = 32

14 x 2 = 28
add 2
28 + 2 =30

12 x 4 = 48
add 2
48 + 2 = 50

Method 3

15 + 2 = 17
add number on the left
17 + 15 = 32

14 + 2 + 16
add number on the left
16 + 14 = 30

12 + 4 = 16
add number on the left
16 + 12 = 28

Patricia


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PostPosted: Tue Aug 20, 2013 7:11 pm 
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Thanks all. It's clear now.


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PostPosted: Tue Aug 20, 2013 8:59 pm 
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Posts: 8228
Rubbish question then unless it makes clear that there is more than possible answer. Does it?


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PostPosted: Wed Aug 21, 2013 7:08 am 
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Joined: Mon Jan 30, 2006 4:07 pm
Posts: 2660
Rubbish Standard form question.

Ok Multiple Choice question as long as only one of the answer appears on the answer sheet. Not the best of questions but children just need to know how to deal with it.

I would always use my usual mantra...

Do not panic if your method does not work, just use your known rules and keep on until you find the answer, do not panic, do not guess.

Some children would have found the right answer within seconds (by chance) others would have plodded through their rules and found it within a minute. Hence why I want children to be ultra quick at adding/subtracting/multiplying/dividing.

Patricia


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