Jack has a total of 20 fifty-cent coins and twenty-cent coins.
He has $5.20 altogether. How many twenty-cent coins does he have?
2 students Lynn and Mala presented their working as shown:
Lynn's working:
50 X 20 = $10.00
$10.00 - $5.20 = $4.80
50 ₵ - 20 ₵ = 30 ₵
$4.80 ÷ 30 = 16
Jack has 16 twenty-cent coins.
Mala's working:
Assume all the coins are twenty cent coins.
Therefore,
50 X 20 = 1000 cents
1000 - 520 = 480 extra cents
50 - 20 = 30 cents
480 ÷ 30 = 16 fifty-cent coins
Whose answer is the best and most logical? Explain your answer. :)
Have fun!
Mrs R
They look the same, but Mala's working is easier to understand
ReplyDeleteMala converted everything to cents, which is like much easier to understand.
DeleteThis looks like a suposition (dunno if spelt correctly!) question.
ReplyDeleteAlthough both workings are same, Mala's working helps does who don't understand the question understand better. But honestly, if in exams, I would rather write down my working like Lynn cuz I do think labeling is a bit waste of time.
unless PSLE really insits on Mala's working, I prefered Lynn's working.
DeleteMrs R., I think u wrote Mala's working wrongly. Why 'assume all are twenty cents coins' when u wrote '50x20'? And at the end, when u found out the no. of twenty cents, u wrote '16 fifty-cents' but for word sentence, u wrote 'Jack has 16 twenty-cent coins.'.
DeleteMrs R, can we post 'Supposition' questions for others to solve too?
Delete_ _
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L
U
Oh ya!Mrs R,I think you really wrote Mala's working wrongly.
DeleteAnd.....can we post questions on supposition and the 'smiley face' questions to let others to solve???
Mrs R, when can we post parallel questions for our classmates to solve?
Deletemalas working is easier to understand
DeleteI think Mala's working is the easiest to understand because:
ReplyDelete1. She has labelled everything correctly like for example :
1000 - 520 = 480 (extra) cents
~ She has labelled what the answer stands for which makes the marker easier to understand. As for Lynn, it would be difficult for both the marker and her to understand the method.
2. Mala converted all the money into cents so that it would be easy for her to calculate. Unlike Lynn's working because Lynn might get confused with the dollars and cents.
If were to answer this question, I would follow what Mrs R taught me.
a) Convert everything into cents
b) Write what each answer stands for
Mala's working is easier to understand because it is all labeled. It will help people who don't understand as it is much clerer than Lynn's working.
ReplyDeleteMala's working.He has labelled everything correctly.
ReplyDeleteI think both are good working and using supposition method.I prefer Mala's workings.
ReplyDeleteMala(good points):
1)Written all the steps clearly
2)Easy to understand
3)Labelled clearly
4)Has written answer statment
Mala(not very good points):
1)They said they want the number of 20 cents so she should have assume all are 50 cents to save time.
2)Should just use dollars to calculate instead of cents
Lynn(good points):
1)Has used dollars instead of cents
2)Assume all are 50 cents instead of 20 cents(which will save time)
3)Has written statment
4)Working clearly done
Lynn(not really good points):
1)Some have units while some don't
2)Not labelled at all
3)Not really easy to understand
To answer this question:
a)Label clearly
b)Do not write the units in the working except for the answer at the end of the working
c)Use dollars to calculate instead of cents
I think she convert into cents is better
DeleteI think it was not 'Mala' who transfered wrongly but Mrs Roman.
DeleteI feel that Mala's working is clearer to understand.She had converted all the dollars into cents,unlike Lynn's working. It will minimize the chances of calculation mistake.Except,there is a error in her assumption. It should be "Assume all the coins are fifty cent coins" .
ReplyDeleteI prefer Mala's working because it is clearly labelled.Therefore,it is easier to understand.
ReplyDeleteMala's working is easier to understand because she labelled all the meanings of the words and converted everything to cents, easier to understand.
ReplyDelete◕‿◕ Smileys!!!
how did u do that smiley face?
Deletecopied from youtube? lol
DeleteI think Mala got confused in her working as even though she put 'assume all are twenty cent coins,' she had done the working by assuming all are fifty cent coins. Then, looking at her final step, she made a mistake again. She type the final step answer as 16 fifty cent coins, but, in her last answer statement, she stated that Jack had 16 twenty cent coins but that does not make sense as she did not state how she got to have 16 twenty cent coins. However,she converted the dollars into cents and that made her working easier to understand. Although Lynn's working made it harder to understand, her working was better as she stated everything clearly and did not make as much mistakes in calculation and transfer errors. Therefore, I prefer Lynn's working!
ReplyDeleteI agree!! :3
DeleteIf it was that mrs roman typed wrongly, then I would prefer Mala's working as it is easier to understand and would make checking even simpler as we can spot calculation errors and transfer errors faster and more efficiently.
DeleteLynn's working:
ReplyDelete50 X 20 = $10.00
$10.00 - $5.20 = $4.80
50 ₵ - 20 ₵ = 30 ₵
$4.80 ÷ 30 = 16
What does this '16' refer to? 16 ducks?
And 'money' divided by 30 'what?' = to 16 'what?'
Jack has 16 twenty-cent coins.
Mala's working:
Assume all the coins are fifty cent coins.
Therefore,
50 X 20 = 1000 cents
1000 - 520 = 480 extra cents
50 - 20 = 30 cents
480 ÷ 30 = 16 twenty-cent coins
Jack has 16 twenty-cent coins.
Mala's method is definitely better and clearer as she converted everything from dollars to cents.
Ha ha...
Deletegood Point in reasoning Lynn's working!
Mala's good points are changing dollars to coins and labeling the numbers. But she could have assume 50cents than 20cents like what Lynn did. That way, she could save time for checking during exams. Now, changing dollars to cents is good as you won't be confused and it is faster. Labeling the numbers would help people to understand better so it won't cause confusion. So I prefer Mala's working as it is CLEAR. :)
ReplyDeleteI mean she could have assume all coins are 50cents than 20cents. :X
DeleteMala's working is easier as she converted dollars into cents.I think in exams if we used Mala's method it would prevent us from having calculation errors when we do similar questions!!
ReplyDeleteThose who think Lynn's method is correct,please be careful because it can cause calculation errors.I also advise you to use Mala's method as it is easier to understand and easier to do!!
That's it from ME!!!
See you again!!!
I prefer Mala's working as she converted the money into cents which is easier to understand.
ReplyDeleteMala's method.It is easier to understand.
ReplyDeleteI agree with marc
Deleteme too
DeleteIt should be Mala's method because he has labelled his working and his working is easier to understand.
ReplyDeleteI prefer Mala's working as he labelled his working unlike lyyn, who did not.
ReplyDelete<(") Nicholas Tan
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ReplyDelete