Q&A - PSLE Math
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tianzhu:
I've been pondering about this question, but I just can't understand this statement:
HiRobertpattinsonidle:
this question seriously mind boggling.
Both shops ABC and XYZ , offered a 15% discount for the same type of mattress. If Mr Muthu were to buy from shop XYZ ,he would have paid $38.25 less than the discounted price in shop ABC. a) What was the discounted price in the shop ABC ?
b) the original price of the mattress in Shop ABC was $1510. what was the minimum percentage discount it must offer so that the discounted price in shop ABC would be lower than the discounted price in Shop XYZ? Give your answer correct to the nearest percent.
This question has been discussed on page 837.
For (a)
15% ------- 38.25
100% ------- 255 (discounted price in ABC)
For (b)
In this case, we are working based on the given original price of $1510
Discounted price in ABC -------- 1510*0.85 ------ 1283.50
Discounted price in XYZ -------- 1283.50 – 38.25 ------- 1245.25
1510 – 1425.25 ------- 264.75
264.75/1510*100% ------- 18%
Best wishes
15% ------- 38.25
100% ------- 255 (discounted price in ABC)
the question states that the difference between XYZ and ABC's discounted price is $38.25.
The discount given by both shops were 15% each. How does one interpret that 15% = 38.25 ? -
mathnoobs:
I've been pondering about this question, but I just can't understand this statement:
Hitianzhu:
[quote=\"Robertpattinsonidle\"]this question seriously mind boggling.
Both shops ABC and XYZ , offered a 15% discount for the same type of mattress. If Mr Muthu were to buy from shop XYZ ,he would have paid $38.25 less than the discounted price in shop ABC. a) What was the discounted price in the shop ABC ?
b) the original price of the mattress in Shop ABC was $1510. what was the minimum percentage discount it must offer so that the discounted price in shop ABC would be lower than the discounted price in Shop XYZ? Give your answer correct to the nearest percent.
This question has been discussed on page 837.
For (a)
15% ------- 38.25
100% ------- 255 (discounted price in ABC)
For (b)
In this case, we are working based on the given original price of $1510
Discounted price in ABC -------- 1510*0.85 ------ 1283.50
Discounted price in XYZ -------- 1283.50 – 38.25 ------- 1245.25
1510 – 1425.25 ------- 264.75
264.75/1510*100% ------- 18%
Best wishes
15% ------- 38.25
100% ------- 255 (discounted price in ABC)
the question states that the difference between XYZ and ABC's discounted price is $38.25.
The discount given by both shops were 15% each. How does one interpret that 15% = 38.25 ?[/quote]hope this helps ...![](\"http://i46.tinypic.com/e66jj6.png\")
http://i46.tinypic.com/e66jj6.png\">
So, for this question, 85% of the difference in discounted price = $38.25
Original difference in price (= A-B, in above model) is 38.25/0.85 = $45
cheers. -
mathnoobs:
HiI've been pondering about this question, but I just can't understand this statement:
15% ------- 38.25
100% ------- 255 (discounted price in ABC)
the question states that the difference between XYZ and ABC's discounted price is $38.25.
The discount given by both shops were 15% each. How does one interpret that 15% = 38.25 ?
This question was first raised in the P5 thread on page 130.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=1290
Also, it has been posted by some members in the P6 thread.
There is one difference for the question in both cases.
a)What was the difference in the original price of the mattress between the two shops?(P5)
b)What was the discounted price in the shop AB? (P6)
For the P5 question, the difference in the original price of the mattress between the two shops is $45.
For P6 question, the discounted price in the shop ABC is $255.
In answering this question, students need to be clear about what is “discounted price”.
It is the price one pays after a discount.
If a book at a retail price of $50 is given a 10% discount, you pay $45.
Best wishes -
tianzhu:
hi
Himathnoobs:
I've been pondering about this question, but I just can't understand this statement:
15% ------- 38.25
100% ------- 255 (discounted price in ABC)
the question states that the difference between XYZ and ABC's discounted price is $38.25.
The discount given by both shops were 15% each. How does one interpret that 15% = 38.25 ?
This question was first raised in the P5 thread on page 130.
http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=68&t=25129&start=1290
Also, it has been posted by some members in the P6 thread.
There is one difference for the question in both cases.
a)What was the difference in the original price of the mattress between the two shops?(P5)
b)What was the discounted price in the shop AB? (P6)
For the P5 question, the difference in the original price of the mattress between the two shops is $45.
For P6 question, the discounted price in the shop ABC is $255.
In answering this question, students need to be clear about what is “discounted price”.
It is the price one pays after a discount.
If a book at a retail price of $50 is given a 10% discount, you pay $45.
Best wishes
this is one of the prelim questions and I think the question was not copied in its entirety.
The question gives only difference in discounted price :
\"Both shops ABC and XYZ , offered a 15% discount for the same type of mattress. If Mr Muthu were to buy from shop XYZ ,he would have paid $38.25 less than the discounted price in shop ABC.\"
So, if the price in shop ABC is $P and price in XYZ is $Q
after discount of 15%, prices would be 85% of $P and 85% of $Q respectively.
then the given price value of $38.25 is
85% of ($P-$Q) = $38.25
therefore, it is not possible to determine the discounted price of XYZ or ABC in this case. But the original difference in price ie ($P-$Q) can be calculated from $38.25 ÷ 85% = $45
Have a great weekend !
For all the PSLE students/mums & dads: take a short breather this weekend (today maybe), before restarting for the final battle. All the best !
cheers. -
MathIzzzFun:
Hi
this is one of the prelim questions and I think the question was not copied in its entirety.
The question gives only difference in discounted price :
\"Both shops ABC and XYZ , offered a 15% discount for the same type of mattress. If Mr Muthu were to buy from shop XYZ ,he would have paid $38.25 less than the discounted price in shop ABC.\"
So, if the price in shop ABC is $P and price in XYZ is $Q
after discount of 15%, prices would be 85% of $P and 85% of $Q respectively.
then the given price value of $38.25 is
85% of ($P-$Q) = $38.25
therefore, it is not possible to determine the discounted price of XYZ or ABC in this case. But the original difference in price ie ($P-$Q) can be calculated from $38.25 ÷ 85% = $45
I don’t have a copy of the latest preliminary papers, so my response to the question was based on what was posted.
It’s still possible to get an answer for discounted price for XYZ based on the given percentage of 38.25.
255 is a possible answer.
Consider this scenario.
The original price in ABC ------- 300
The discounted price in ABC ------ 0.85*300 ------ 255
The original price in XYZ ------- 255
The discounted price in XYZ ------ 0.85*255 ------ 216.75
Difference in original price ------- 300 – 255 ------ 45
Difference in discounted price ------- 255 – 216.75------ 38.25
Best wishes -
tianzhu:
255 is one of the uncountable answers.
HiMathIzzzFun:
this is one of the prelim questions and I think the question was not copied in its entirety.
The question gives only difference in discounted price :
\"Both shops ABC and XYZ , offered a 15% discount for the same type of mattress. If Mr Muthu were to buy from shop XYZ ,he would have paid $38.25 less than the discounted price in shop ABC.\"
So, if the price in shop ABC is $P and price in XYZ is $Q
after discount of 15%, prices would be 85% of $P and 85% of $Q respectively.i
then the given price value of $38.25 is
85% of ($P-$Q) = $38.25
therefore, it is not possible to determine the discounted price of XYZ or ABC in this case. But the original difference in price ie ($P-$Q) can be calculated from $38.25 ÷ 85% = $45
I don’t have a copy of the latest preliminary papers, so my response to the question was based on what was posted.
It’s still possible to get an answer for discounted price for XYZ based on the given percentage of 38.25.
255 is a possible answer.
Consider this scenario.
The original price in ABC ------- 300
The discounted price in ABC ------ 0.85*300 ------ 255
The original price in XYZ ------- 255
The discounted price in XYZ ------ 0.85*255 ------ 216.75
Difference in original price ------- 300 – 255 ------ 45
Difference in discounted price ------- 255 – 216.75------ 38.25
Best wishes
It can be 300, 2580, any number as long as the difference in origianl price is $45. eg 300 n 345, 2580 n 2625 etc.
So, it is not possible to determine only one price.
cheers. -
MathIzzzFun:
Hi
255 is one of the uncountable answers.
It can be 300, 2580, any number as long as the difference in origianl price is $45. eg 300 n 345, 2580 n 2625 etc.
So, it is not possible to determine only one price.
cheers.
We are asked to find the discounted price of ABC without given the original price in (a).Hence,there would be multiple answers.
Based on the question as posted by Essential,255 is certainly a possibility.
Perhaps, the question in the P5 thread is better crafted.
a)What was the difference in the original price of the mattress between the two shops?(P5)
Best wishes -
first, I must clarify that my query was on the P6 version, not the P5 version. I fully comprehend the P5 version, that makes sense.
For the P6 version, I too was of the opinion that something was not quite right. To have a question that has multiple answers is unfair, especially under exam conditions. At the very least, they should have constrained the answer to a single value by giving some additional conditions.
anyways, thanks Tianzhu and MathIzzFun for clearing my doubts. I was on the track that there was only one possible solution, and could not comprehend why 15% = 38.25. Now I know that 15% could represent a number of possible values, not just 38.25. Actually, the condition is based on the difference between the discounted price, and there are infinite values that satisfy that condition.
actually, I just realized that the student can write any numerical answer and it will still be right. Am I right to say this ?
if this is so , then all students would have scored in this question, because there are no wrong answers for this question. This would be a 'gift' question then. hey, I do like this question after all
wait, no, not any values, just any values greater than 38.25. -
mathnoobs:
HiFor the P6 version, I too was of the opinion that something was not quite right. To have a question that has multiple answers is unfair, especially under exam conditions. At the very least, they should have constrained the answer to a single value by giving some additional conditions.
If a question is crafted correctly, there should be only one correct answer.
If not, there is a possibility of multiple answers.
Ideally it should not happen, but realistically it is an inescapable fact of life that we are living in an imperfect world.
These are some examples of questions discussed in this forum which have multiple answers.
1) Dean,Ellen and Andy shared a box of sweets in the ratio of 3:4:5 and there was 4 left .They put the 4 sweets into a second box which contained 1/8 fewer sweets than the first box, and shared the sweets in the same ratio as before,and this time there were no remainder.
A)Find the total number of sweets they shared in the first round.
B)Find the total number of sweets each child received in both rounds of sharing.
2) Jenny bought some strawberries and wanted to put them into boxes. If she put 4 strawberries into each box, there will be 3 strawberries left. If she put 6 strawberries into each box, there will be 5 strawberries left.
(a) If the nos. of strawberries is btw 100 - 150, how many strawberries did Jenny buy?
(b) If Jenny decided to put all strawberries equally into 16 bags, what is the minimum nos. of bag she would need?
Best wishes -
mathnoobs:
Hi
actually, I just realized that the student can write any numerical answer and it will still be right. Am I right to say this ?
No, not any numerical values.
Based on the question as in part (a) in the P6 thread, the answers can be any values satisfying this condition.
\"The difference in original prices between ABC and XYZ is 45\".
Best wishes
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