Help needed: is there missing info in this question?
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Help needed: is there missing info in this question?
This is from a paper that has at least one question with missing info (typographical error). Is this question also missing information or are we just innumerate?
30 children are going on a trip. The trip is £5 with lunch provided or £3 without. The 30 children pay a total of £110. How many paid £3?
30 children are going on a trip. The trip is £5 with lunch provided or £3 without. The 30 children pay a total of £110. How many paid £3?
Re: Help needed: is there missing info in this question?
I think its complete; I'd use trial and improvement.
If all 30 paid £3 then £90 would be collected, so we know some pay £5. I also noted we need a multiple of 3 that gives a zero in the units. There aren't many to try.
Try 20 paying £3 and 10 paying £5; £60 + £50 = £110
If all 30 paid £3 then £90 would be collected, so we know some pay £5. I also noted we need a multiple of 3 that gives a zero in the units. There aren't many to try.
Try 20 paying £3 and 10 paying £5; £60 + £50 = £110
Re: Help needed: is there missing info in this question?
I think it’s doable. I’ve been used simultaneous equations to solve it though, which wouldn’t be a method used for 11+, if this is an 11+question, suspect trial and improvement would be the way to go
Cross post with G55
Cross post with G55
Re: Help needed: is there missing info in this question?
Yes, I spoke to a primary school teacher who said that it is a key stage 2, level 5 question. Very few children would solve it and most would use trial and improvement.
It is from a practice paper provided by a company, but is from an old SATS paper.
It is from a practice paper provided by a company, but is from an old SATS paper.
Re: Help needed: is there missing info in this question?
You could use algebra but that is not part of KS2 - noticing that you need a multiple of 3 which gives a unit's digit of 0 means it needs few trials
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Re: Help needed: is there missing info in this question?
I tackled it a bit differently (I think). If all 30 paid £3 the total would be £90 which is £20 short of the real total, so we know that 10 children paid an extra £2, the difference between £110 and £90, and the other 20 paid £3. No trial and improvement needed?
Could be done in reverse of course. Assume all 30 paid £5, making £150, therefore 20 children must have paid £2 less to bring the £150 down to £110.
Could be done in reverse of course. Assume all 30 paid £5, making £150, therefore 20 children must have paid £2 less to bring the £150 down to £110.
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Re: Help needed: is there missing info in this question?
A man after my own heart ...anotherdad wrote:I tackled it a bit differently (I think). If all 30 paid £3 the total would be £90 which is £20 short of the real total, so we know that 10 children paid an extra £2, the difference between £110 and £90, and the other 20 paid £3. No trial and improvement needed?
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Re: Help needed: is there missing info in this question?
This is a trail and error question. 20 children paid £3, which makes £60. 10 children paid £5 each, which makes £50.IrisM65 wrote:This is from a paper that has at least one question with missing info (typographical error). Is this question also missing information or are we just innumerate?
30 children are going on a trip. The trip is £5 with lunch provided or £3 without. The 30 children pay a total of £110. How many paid £3?
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Re: Help needed: is there missing info in this question?
I just asked my 10 yr old, and she did it this way:
If all 30 paid £5 each, the total cost would be £150.
The total cost was £110, so £40 less than this.
That £40 means 20 children paid £2 less each (based on £3 being £2 less than £5.)
So 20 paid £3 each and 10 paid £5 each = £110
I did trial and improvement (before asking dd, otherwise I’d have realised her way was much better!)
30 x £5 = £150
30 x £3 = £90
I need to be just under halfway between these totals, so I’ll try over half the children paying £3 and under half paying £5. So:
20 x £3 = £60 and 10 x £5 = £50. Total £110.
That was partly a lucky guess, but if it had been over / under, I’d have adjusted accordingly.
My daughter’s way was more efficient, but it’s doable either way.
If all 30 paid £5 each, the total cost would be £150.
The total cost was £110, so £40 less than this.
That £40 means 20 children paid £2 less each (based on £3 being £2 less than £5.)
So 20 paid £3 each and 10 paid £5 each = £110
I did trial and improvement (before asking dd, otherwise I’d have realised her way was much better!)
30 x £5 = £150
30 x £3 = £90
I need to be just under halfway between these totals, so I’ll try over half the children paying £3 and under half paying £5. So:
20 x £3 = £60 and 10 x £5 = £50. Total £110.
That was partly a lucky guess, but if it had been over / under, I’d have adjusted accordingly.
My daughter’s way was more efficient, but it’s doable either way.
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Re: Help needed: is there missing info in this question?
Only just read anotherdad’s reply properly and realised that dd’s method has already been suggested. Will leave it there in case seeing the steps she used is useful.