Q&A - P5 Math

[speedmaths.012624com]

happyheart:

Appreciate help on this please.


Q) Carol bought 4.9kg of coffee powder. Amanda bought 400g more coffee powder than Carol. After both of them use the same amount of coffee powder, Amanda has twice as much coffee powder as Carol. How much coffee powder did each of them use?

Hi,

For ALL such Double-Ratios questions, you may use the Advanced Model Method (or Bags and Boxes Method).

Carol bought 4.9kg of coffee powder.
Amanda bought 4.9kg + 400g = 5.3kg of coffee powder.

Let Carol put her coffee powder in 1 Bag and 1 Box.
Let Amanda put her coffee powder in 1 Bag and 2 Boxes.

(For those used to the normal Bar Model Method, think of, or imagine, a Box as a Rectangle, and a Bag as a Circle)

Amanda → 5.3kg → 1 Bag and 2 Boxes
Carol → 4.9kg → 1 Bag and 1 Box

(Both of them use the same amount of coffee powder)
Both of them use 1 Bag of coffee powder each

(Amanda has twice as much coffee powder as Carol)
Carol had 1 Box of coffee powder left.
Amanda had 2 Boxes of coffee powder left.

Amanda → 5.3kg → 1 Bag and 2 Boxes
Carol → 4.9kg → 1 Bag and 1 Box

5.3kg → 1 Bag and 2 Boxes\t(Row 1)
4.9kg → 1 Bag and 1 Box\t(Row 2)

(Row 1 – Row 2)

0.4kg → 0 Bag and 1 Box
0.4kg → 1 Box

4.9kg → 1 Bag and 1 Box\t(Row 2)
4.9kg → 1 Bag and 0.4kg
4.5kg → 1 Bag

Both of them use 1 Bag of coffee powder each

Each of them used 4.5kg of coffee powder.

Cheers


speedmaths.com


.

[ozora]

need some guide in this question. Tank A and Tank B are identical. Tank A is 2/5 full of water while tank B is 6/7 full of water. The mass of Tank A with its contents is 7/10 of The mass of Tank B with its contents. The total mass of the 2 tanks and their contents is 374kg. Find the mass of an empty tank.

[MathIzzzFun]

ozora:

need some guide in this question. Tank A and Tank B are identical. Tank A is 2/5 full of water while tank B is 6/7 full of water. The mass of Tank A with its contents is 7/10 of The mass of Tank B with its contents. The total mass of the 2 tanks and their contents is 374kg. Find the mass of an empty tank.

Hi

mass of tank A with contents --> 7/17 x 374 kg = 154 kg
mass of tank B with contents --> 374 kg - 154 kg = 220 kg
(6/7-2/5)tank of water --> 220 - 154 = 66 kg
16/35 tank of water --> 66 kg
mass of tank = 220 - 6/7 tank of water = 220 - 30/16 x 66 = 96.25 kg
(** 6/7 tank of water = 30/35 tank of water = 30/16 x 66 kg)

most schools are teaching/doing ratio sums at the moment, here's alternate approach using ratio:
difference in mass of tanks with contents = difference in mass of contents
mass of water in tank A : tank B = 2/5 : 6/7 = 7 : 15
mass of tank A with contents : tank B with contents = 7 : 10
\"equalize\" the difference:
mass of water in tank A : tank B = 21u : 45u
mass of tank A with contents : tank B with contents = 56u : 80u
mass of tank = 56u - 21u = 80u-45u = 35u
total mass of both tanks with contents = 136u
mass of tank = 35/136 x 374 = 96.25 kg


cheers.

[Bolt]

Please help


16) There are some crystal and glass marbles in a pouch. If 3 crystal marbles are removed from the pouch, the number of crystal marbles left will be 1/6 of the glass marbles left. If 5 glass marbles are removed from the pouch, the number of crystal marbles left will be 1/4 of the glass marbles left. How many marbles are there in the pouch at first?

[MANGO STAR]

Hi,


can someone pls help with this question.

Weichong and Rama collect stamps. If Rama gives Weichong 15 stamps, he will have the same number of stamps as Weichong. If Weichong gives Rama 15 stamps, he will have 1/2 as many stamps as Rama. How many stamps does each boy have?

[tianzhu]

MANGO STAR:

Hi,


can someone pls help with this question.

Weichong and Rama collect stamps. If Rama gives Weichong 15 stamps, he will have the same number of stamps as Weichong. If Weichong gives Rama 15 stamps, he will have 1/2 as many stamps as Rama. How many stamps does each boy have?

Hi

Hope this helps.

Best wishes.

http://farm8.staticflickr.com/7043/7134329007_e0a139ea17_z.jpg\">

[MathIzzzFun]

Bolt:

Please help


16) There are some crystal and glass marbles in a pouch. If 3 crystal marbles are removed from the pouch, the number of crystal marbles left will be 1/6 of the glass marbles left. If 5 glass marbles are removed from the pouch, the number of crystal marbles left will be 1/4 of the glass marbles left. How many marbles are there in the pouch at first?

hi
the question is not set properly - as it is, the number of marbles is not a whole number. I suspect the sentence \"the number of crystal marbles left will be 1/6 of the glass marbles left.\" should instead be \"the number of crystal marbles left will be 1/6 of the marbles left.\"

any way, here is the solution for the question as is, using MD...

http://i50.tinypic.com/2u9ua9x.png\">

cheers.

[MANGO STAR]

Hi Tianzhu,


thank you so much. I’ve been cracking my head with this sum but u jus solve it so easily. I think i have to go to sch with my son liao !!! Hahaha!!

My old rusty brain.

[tianzhu]

MANGO STAR:

Hi Tianzhu,


thank you so much. I've been cracking my head with this sum but u jus solve it so easily. I think i have to go to sch with my son liao !!! Hahaha!!

My old rusty brain.

Hi

You’re welcome.

Sometimes life leaves us with no choice but to “go to school with our kids”.

Enjoy the journey.

Best wishes

[Bolt]

thank you, got it.