Q&A - PSLE Math
-
Neat:
HiHi morning,
Please assist on the following question:
30% of the books in a library were fiction, 25% of them were non-fiction and the rest were reference books. After 200 more fiction and non-fiction books were ordered, the percentage of the reference books in the library decreased to 40% and the number of fiction books increased by 10%. How many non-fiction books were ordered?
Thanks vm
You may use MD or UM.
FB:NFB:RB ----- 30%:25%:45% -------6u:5u:9u
RB remained unchanged.
40% ------ 9u
60% ------- 13.5u
13.5u ------- 11u + 200
1u ------ 80
Number of FB at first ------6*80 -------480
Number of FB in the end ------ 528 (10% increase)
Number of FB and NFB in the end ------13.5*80 ------1080
Number of NFB in the end ------- 1080 – 528 ------552
Number of NFB at first ------ 5*80 ------- 400
552 – 400 --------152
Number of NFB ordered ------152
Best wishes -
Superbugs:
Tks a lot! I realised my mistake.[/quote]You're welcome.
Actually, if Me is 100%, Sister is not 80% (this means \"Me\" had 1/4 more than Sister), but instead is 100%*5/6=83 1/3%. This is so that 1/5 of Sister added to Sister will give \"Me\".mathfreak:
[quote=\"Superbugs\"]Nan Hua CA1 P6 2011
Q14.
My salary is 1/5 more than my sister but 20% less than my brother. If our total salary is $11,100, what is my sister's salary?
If Me=100%
Brother =120%
Sister=80%
80/300x11,100=2960
but answer is $3000?
Pls assist. Tks
Brother is also not 120% (this means \"Me\" had 16 2/3% less than Brother), but instead is 100%*5/4=125%. This is so that 20% of Brother subtracted from Brother will give \"Me\".
The total would be 308 1/3%, which means 83 1/3% is $3000.
-
Superbugs:
HiNan Hua CA1 P6 2011
Q7:
I have some red and blue ribbons in a bottle.
If I add in 20 red ribbons, 60% of my ribbons are blue.
If I add in another 60 blur ribbons, 75% of my ribbons are blue.
How many ribbons have I in the bottle?
Please help with this question. Tks
This question has been floating around in forums regularly.
It was discussed in our earlier posts. Depending on one’s interpretation of the word another in the second condition, one may end up with 180 or 80.
It’ll be helpful if current PSLE students or their parents help to clarify with their school teachers on this question.
Condition1
Red : Blue -------- change add 20 red ribbons
2u:3u
Condition 2
Red : Blue -------- change add 60 blue ribbons
1p:3p
2u – 20 ------- 1p
3u + 60 -------3p
Equalising the parts
6u – 60 -------3p
3u + 60 ------- 6u - 60
3u ------ 120
1u ------ 40
Number of ribbons at first ------ (5*40) - 20 ------180
Best wishes -
Hi, please help me with this question.
Evergreen School spent $9065 on some tennis rackets and badmintob rackets. The ratio of the number of tennis rackets bought to the number of badminton rackets bought was 5:7. A tennis rackets costs $13.30 more than a badminton racket. The total cost of the tennis racket was 17/20 of the total cost of the badminton rackets. Find the cost of the one such tennis racket.
Thanks. -
notfreemom:
HiHi, please help me with this question.
Evergreen School spent $9065 on some tennis rackets and badmintob rackets. The ratio of the number of tennis rackets bought to the number of badminton rackets bought was 5:7. A tennis rackets costs $13.30 more than a badminton racket. The total cost of the tennis racket was 17/20 of the total cost of the badminton rackets. Find the cost of the one such tennis racket.
Thanks.
One neat way is to use MD.Due to time constraints, I'll give some pointers.
The total cost of the tennis racket was 17/20 of the total cost of the badminton rackets.Evergreen School spent $9065 on some tennis rackets and badminton rackets.
Hence, tennis rackets ------- 4165 and badminton rackets ------ 4900
The ratio of the number of tennis rackets bought to the number of badminton rackets bought was 5:7
7 units ------ 4900
1 unit ------ 700
4165 – (5*700) ------- 665
Number of tennis rackets ------ 665/13.3 -------50
Cost of 1 tennis racket ------ 4165/50 ------ 83.3
Best wishes -
Thanks for our prompt reply. I appreciate it very much.
-
tianzhu:
[quote]Thanks tianzhiu :congrats: [/quote]
HiNeat:
Hi morning,
Please assist on the following question:
30% of the books in a library were fiction, 25% of them were non-fiction and the rest were reference books. After 200 more fiction and non-fiction books were ordered, the percentage of the reference books in the library decreased to 40% and the number of fiction books increased by 10%. How many non-fiction books were ordered?
Thanks vm
You may use MD or UM.
FB:NFB:RB ----- 30%:25%:45% -------6u:5u:9u
RB remained unchanged.
40% ------ 9u
60% ------- 13.5u
13.5u ------- 11u + 200
1u ------ 80
Number of FB at first ------6*80 -------480
Number of FB in the end ------ 528 (10% increase)
Number of FB and NFB in the end ------13.5*80 ------1080
Number of NFB in the end ------- 1080 – 528 ------552
Number of NFB at first ------ 5*80 ------- 400
552 – 400 --------152
Number of NFB ordered ------152
Best wishes -
Neat:
[quote]Thanks tianzhiu :congrats: [/quote][/quote][quote]Sorry! :oops: :thankyou: [/quote]
Hitianzhu:
[quote=\"Neat\"]Hi morning,
Please assist on the following question:
30% of the books in a library were fiction, 25% of them were non-fiction and the rest were reference books. After 200 more fiction and non-fiction books were ordered, the percentage of the reference books in the library decreased to 40% and the number of fiction books increased by 10%. How many non-fiction books were ordered?
Thanks vm
You may use MD or UM.
FB:NFB:RB ----- 30%:25%:45% -------6u:5u:9u
RB remained unchanged.
40% ------ 9u
60% ------- 13.5u
13.5u ------- 11u + 200
1u ------ 80
Number of FB at first ------6*80 -------480
Number of FB in the end ------ 528 (10% increase)
Number of FB and NFB in the end ------13.5*80 ------1080
Number of NFB in the end ------- 1080 – 528 ------552
Number of NFB at first ------ 5*80 ------- 400
552 – 400 --------152
Number of NFB ordered ------152
Best wishes -
mathfreak:
Could you pls advise if this can be solved by model method. My DD was confused with the percentage method.
Actually, if Me is 100%, Sister is not 80% (this means \"Me\" had 1/4 more than Sister), but instead is 100%*5/6=83 1/3%. This is so that 1/5 of Sister added to Sister will give \"Me\".Superbugs:
Nan Hua CA1 P6 2011
Q14.
My salary is 1/5 more than my sister but 20% less than my brother. If our total salary is $11,100, what is my sister's salary?
If Me=100%
Brother =120%
Sister=80%
80/300x11,100=2960
but answer is $3000?
Pls assist. Tks
Brother is also not 120% (this means \"Me\" had 16 2/3% less than Brother), but instead is 100%*5/4=125%. This is so that 20% of Brother subtracted from Brother will give \"Me\".
The total would be 308 1/3%, which means 83 1/3% is $3000. -
Hi notfreemom and Neat
You’re welcome.
Best wishes
Hello! It looks like you're interested in this conversation, but you don't have an account yet.
Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.
With your input, this post could be even better 💗
Register Login