Tutor MathsGuru: Ask me for your burning Maths questions!

[CoffeeCat]

OngMum:

Hi Mathsguru, we need your guidance on the below questions.


Qn 1, Shop A has 156kg of rice while Shop B has 72kg of rice. Each shop sold an equal amount of rice and after that the ratio of the amount of rice left in their shop was 4:1. Find out how much rice has been sold.

Qn 2, 6/14 of the chairs in the hall are in rows of 13. Half of the chairs in the hall are in rows of 7. There are 112 more chairs in rows of 7. The rest of the chairs are stacked up. Find out the total number of chairs in the hall.

Many thanks.

Cheers!

this is so 2007 psle questions. view here
http://sc-math.com/math-talk/math-psle073.php for solution

[OngMum]

Many thanks to you, CoffeeCat!

Cheers!

[Tang]

CoffeeCat:

OngMum:

Hi Mathsguru, we need your guidance on the below questions.


Qn 1, Shop A has 156kg of rice while Shop B has 72kg of rice. Each shop sold an equal amount of rice and after that the ratio of the amount of rice left in their shop was 4:1. Find out how much rice has been sold.

Qn 2, 6/14 of the chairs in the hall are in rows of 13. Half of the chairs in the hall are in rows of 7. There are 112 more chairs in rows of 7. The rest of the chairs are stacked up. Find out the total number of chairs in the hall.

Many thanks.

Cheers!

this is so 2007 psle questions. view here
http://sc-math.com/math-talk/math-psle073.php for solution

You may want to refer
http://prischoolmaths.blogspot.com/search/label/_PSLE07 for the correct wordings for Qn 2.

[firebird]

Dear Mathsguru


I am totally lost on the following P6 maths, especially question 1, which look easy, but i could not do, please help:

1) Victor wants to travel from Town X to Town Y. If he drives at an average speed of 60km/h, he would reach Town Y at 10.30am. If he drives at an average speed of 80km/h, he would reach Town Y at 9.30am.

(a) Find the distance between Town X and Town Y .

(b) At what average speed should he drive if he wants to reach Town Y at 9.30 am?

2) A piggy bank contained some fifty-cents coins and twenty-cents coins in the ratio of 5:2. When 36 fifty-cents coins were taken out and replaced by the same number of twenty-cents coins, the ratio of the number of fifty-cents coins to twenty-cents coins became 1:4.

a) What was the value of the twenty-cents coins at first?
b) How much money was in the piggy bank at first?

[firebird]

Dear mathsguru


Very sorry not thanking before sign off earlier

Regards
firebird

[Vanilla Cake]

Dear Mathsguru,

Pls help to provide solution for this RGPS P6 SA1 2009 P2 Q18:

Container A contains 250 red marbles and 200 blue marbles. Container B contains 600 red marbles and 150 blue marbles. How many red and blue marbles must be moved from Container A to Container B such that 25% of the marbles in Container A are red and 75% of the marbles in Container B are red? (5 marks)

Thanks

[Muffins]

Hi Vanilla Cake, Tang has addressed this question in the PSLE-Math thread. The answer is: A – 25 : 75 = 1 : 3


B – 75 : 25 = 3 : 1

A + 3 B –> 250 + 600 = 850

3 A + B –> 200 + 150 = 350

4 A + 4 B –> 850 + 350 = 1200
1 A + 1 B –> 1200 / 4 = 300

2 B –> 850 - 300 = 550
B –> 550 / 2 = 275

2 A –> 350 - 300 = 50
A –> 50 / 2 = 25

250 - 25 = 225 red

200 - 25 x 3 = 125 blue (or 275 - 150 = 125 blue)

So move 225 red marbles and 125 blue marbles from Container A to Container B.

[CoffeeCat]

i think vanilla is hoping for mathsguru to come up with an alternative solution based on models.

[Muffins]

Oh... :imsorry:

[Vanilla Cake]

CoffeeCat:

i think vanilla is hoping for mathsguru to come up with an alternative solution based on models.

Yes, CoffeeCat. You are right, I am looking for alternative solution based on models from Mathsguru besides the solution using simultaneous equations as posted by Tang.

Muffins:

Oh... :imsorry:

It's ok. . You are cute!

firebird:

1) Victor wants to travel from Town X to Town Y. If he drives at an average speed of 60km/h, he would reach Town Y at 10.30am. If he drives at an average speed of 80km/h, he would reach Town Y at 9.30am.

(a) Find the distance between Town X and Town Y .
(b) At what average speed should he drive if he wants to reach Town Y at 9.30 am?

\"At what average speed should he drive if he wants to reach Town Y at 9.30 am?\", is there a typo error?

(a) Distance between Town X and Town Y is 240 km
Difference in speed = (80-60) km/h = 20 km/h.
60÷20=3
3 x 80 = 240 km

OR

use algebra, let number of hours taken to travel at 80 km/h be n.
80n = 60(n+1)
80n = 60n + 60
20n = 60
n = 3

80x3 = 240 km

OR

Wait for Mathguru's solutions to be posted.

2) A piggy bank contained some fifty-cents coins and twenty-cents coins in the ratio of 5:2. When 36 fifty-cents coins were taken out and replaced by the same number of twenty-cents coins, the ratio of the number of fifty-cents coins to twenty-cents coins became 1:4.

a) What was the value of the twenty-cents coins at first?
b) How much money was in the piggy bank at first?

(a)
Before
50¢ coins : 20¢ coins
5 : 2
25 : 10

After
50¢ coins : 20¢ coins
1 : 4
7 : 28

Ratio: Make the total (before)->25+10=35 and total (after)->7+28=35 be equal.

18u=36
10u =20

20x 20 cents = 400 cents = $4.00
At first, value of twenty-cents coins was $4.00

(b)
25u = 50
50 x 50 cents = 2500 cents = $25

$(25+4) = $29
At first, amount of money in the piggy bank was $29

OR

Wait for Mathguru's solutions to be posted.