Q&A - PSLE Math

[Neat]

Hi!


I need explanation on the following question:

A large warehouse had a total of 2180 black, red and white T-shirts for sale. The ratio of the number of black T-shirts to the number of red T-shirts was 3:1. After 2/5 of the black T-shirts, 1/3 of the white T-shirts and none of the red T-shirts were sold on the first day, there were 1504 T-shirts left. How many red T-shirts did the warehouse have at first?

B : R : W Total
Before 3 : 1 : ? 2180
Sold -2/5 0 -1/3 676
After 3/5 1 2/3 1504

The working given in the paper is 6u + 1p = 676
12u + 2p = 676 x 2 = 1352
14u + 2p = 1504
2u = 1504-1352 = 152
5u = (152/2) x 5 = 380

My question is why 6u + 1p = 676? I thought we should find the
common factor for 2/5 and 1/3?

Please enlighten.
Thanks

[MathIzzzFun]

Neat:

Hi!


I need explanation on the following question:

A large warehouse had a total of 2180 black, red and white T-shirts for sale. The ratio of the number of black T-shirts to the number of red T-shirts was 3:1. After 2/5 of the black T-shirts, 1/3 of the white T-shirts and none of the red T-shirts were sold on the first day, there were 1504 T-shirts left. How many red T-shirts did the warehouse have at first?

B : R : W Total
Before 3 : 1 : ? 2180
Sold -2/5 0 -1/3 676
After 3/5 1 2/3 1504

The working given in the paper is 6u + 1p = 676
12u + 2p = 676 x 2 = 1352
14u + 2p = 1504
2u = 1504-1352 = 152
5u = (152/2) x 5 = 380

My question is why 6u + 1p = 676? I thought we should find the
common factor for 2/5 and 1/3?

Please enlighten.
Thanks

Hi

hope this helps..

At first --- Black : Red : White = 15u : 5u : 3p
Sold --- Black : Red : White = 6u : 0 : 1p ---> 6u + 1p = 2180-1504 = 676
Left --- Black : Red : White = 9u : 5u : 2p --> 14u + 2p = 1504

cheers.

[beanbear]

Hi Can someone help with this:


Phoebe’s annual expenditure is 2/5 less than Chloe’s and 1/5 more than Denise. If they spent $34020 in a year altogether, find Denise’s monthly expenditure.

[Bunny27]

beanbear:

Hi Can someone help with this:


Phoebe's annual expenditure is 2/5 less than Chloe's and 1/5 more than Denise. If they spent $34020 in a year altogether, find Denise's monthly expenditure.

Hi, someone pls help on this question:


1) Jack, Kristine and Lina painted some chairs for their school classrooms. Jack painted ½ of the numbers of the chairs.
Kristine and Lina painted the remaining number of chairs in the ratio of 3:5.
Jack painted 65 more chairs than Kristine.
(a) How many chairs did Jack and Lina paint together?
(b) The school would save $4 for every chair painted, what was the total savings for the school?

:thankyou:

[MathIzzzFun]

Bunny27:

beanbear:

Hi Can someone help with this:


Phoebe's annual expenditure is 2/5 less than Chloe's and 1/5 more than Denise. If they spent $34020 in a year altogether, find Denise's monthly expenditure.

Hi, someone pls help on this question:


1) Jack, Kristine and Lina painted some chairs for their school classrooms. Jack painted ½ of the numbers of the chairs.
Kristine and Lina painted the remaining number of chairs in the ratio of 3:5.
Jack painted 65 more chairs than Kristine.
(a) How many chairs did Jack and Lina paint together?
(b) The school would save $4 for every chair painted, what was the total savings for the school?

:thankyou:

Hi
Jack:Kris:Lina --> 8u:3u:5u
So, 8u-3u=5u -->65
1u--> 13
Jack & Lina -->13 x 13 = 169chairs.
..Can u complete the rest?

cheers.

[MathIzzzFun]

beanbear:

Hi Can someone help with this:


Phoebe's annual expenditure is 2/5 less than Chloe's and 1/5 more than Denise. If they spent $34020 in a year altogether, find Denise's monthly expenditure.

Hi
Chloe:Phoebe=5:3
Phoebe:Denise =6:5
Chloe:Phoebe:Denise = 10u:6u:5u --- Total --> 21u
21u --> $34020, 1u-->$1620
Denise's monthly expenditure = $1620×5÷12 =$675

cheers.

[Bunny27]

MathIzzzFun:

Bunny27:

[quote=\"beanbear\"]Hi Can someone help with this:


Phoebe's annual expenditure is 2/5 less than Chloe's and 1/5 more than Denise. If they spent $34020 in a year altogether, find Denise's monthly expenditure.

Hi, someone pls help on this question:


1) Jack, Kristine and Lina painted some chairs for their school classrooms. Jack painted ½ of the numbers of the chairs.
Kristine and Lina painted the remaining number of chairs in the ratio of 3:5.
Jack painted 65 more chairs than Kristine.
(a) How many chairs did Jack and Lina paint together?
(b) The school would save $4 for every chair painted, what was the total savings for the school?

:thankyou:

Hi
Jack:Kris:Lina --> 8u:3u:5u
So, 8u-3u=5u -->65
1u--> 13
Jack & Lina -->13 x 13 = 169chairs.
..Can u complete the rest?

cheers.[/quote]
Sure. Thank you for the help!

[MathIzzzFun]

AJH:

Hi -


Q. Jane and May share a box of beads. If Jane were to give 25% of her share to May, Jane would have half of May's final share. If Jane were to give 16 beads to May, Jane would have 54 fewer beads than May. If they were to pack all their beads into boxes of 25 each, what is the least number of boxes required to pack all of them?

Thank you.

Hi

You can see the solution quite easily with MD... I will use units to save time.

If Jane were to give 16 beads to May, Jane would have 54 beads fewer than May
After:
Jane --> 4 units
May --> 4 units + 54
At first:
Jane -->4 units + 16
May --> 4 units + 38

If Jane were to give 25% of her share to May, Jane would have half of May's final share.
1/4 of Jane's share --> 1 unit + 4
After:
Jane --> 3 units + 12
May --> 5 units + 42 = 2 x (3 units+12)
5 units + 42 = 6 units + 24
1 unit --> 18

Number of beads each had:
Jane --> 4 x 18 + 16 = 88
May --> 4 x 18 + 38 = 110
..I believe you can carry on from here..

cheers.

[yomemai]

For maths, you should really use algebra because it is easy to understand, easy to score marks with and approved by MOE. :imcool:

[ksasalways]

For those who are thinking of how to help your child excel in the coming PSLE math, I received note that HCI is organising a Mathematics Workshop run by an experienced trainer, targeting the current Primary 5 & 6 students to excel in their PSLE mathematics.


Thoughts some of the parents who are thinking of sending your child IP school like HCI might want to consider writing to them at [email protected] for details and registration.

The first of the two parts workshop details:
Topics : Area, Volume, Angle and Speed.
Date : 14 July 2012 (Saturday)
Time : 9.15 am. to 12.15 pm. (Tea break from 10.15 am. to 10.35 am.)
Venue : HCI High School Section Lecture Theatre 2
Who should attend : Parents and P5 & P6 Children
Registration Fee : Per Adult : $20
Per Child: $10
Walk in : Per Adult : $25 and Per Child : $ 15
Registration Deadline : 7 July 2012