Q&A - PSLE Math

[MathIzzzFun]

imacsg:

Can anyone help? Thanks.

A shop sold cupcakes at $2.50 each and tarts at $5.30 each. Apple bought some cupcake while Mark bought some tarts. Mark spent $5.20 more than Apple but bought 8 fewer items than her.

How many tarts did Mark buy?
How much money did Apple spend?

assume that Mark bought same number of tarts --> 8 more
8 x $5.30 = $42.40
$42.40 + $5.20 = $47.60 --> Mark would have spent $47.60 more than Apple he bought same number of tarts as cupcakes bought by Apple.

$5.30 - $2.50 = $ 2.80 --> 1 tart cost $ 2.80 more than a cupcake.
Number of cupcakes bought by Apple = $47.60 / $ 2.80 = 17
Apple spent --> 17 x $2.50 = $42.50
Number of tarts bought by Mark = 17 - 8 = 9

cheers.

[imacsg]

Thanks for your help.

[bluie79]

Hi


Does anyone know how to solve this question? My niece asked me and I cant seem to solve it. The question goes like this:

Pearly had 20% more marbles than Sandy. Then Pearly gave away 30% of her marbles to her sister. Sandy received 65 marbles from Joe. As a result, Sandy now had 26% more marbles than Pearly. How many marbles did Pearly have at first?
Thanks a Mil!!

bluie79

[MathIzzzFun]

bluie79:

Hi


Does anyone know how to solve this question? My niece asked me and I cant seem to solve it. The question goes like this:

Pearly had 20% more marbles than Sandy. Then Pearly gave away 30% of her marbles to her sister. Sandy received 65 marbles from Joe. As a result, Sandy now had 26% more marbles than Pearly. How many marbles did Pearly have at first?
Thanks a Mil!!

bluie79

pls check the highlighted figure - is this supposed to be 25% ?

cheers.

[happyheart]

MathIzzzFun:

happyheart:

Hi, one more please. I am always confused when there is transfer back and forth.Thanks.


Jack and Aqil had some game cards. If Jack gave Aqil 52 cards, he would have the same number of cards as Aqil. If Aqil gave Jack 34 cards, the ratio of the number of cards Aqil had to the number of cards Jack had would be 3:7.How many cards did Jack have at first?

If Jack gave Aqil 52 cards, he would have the same number of cards as Aqil
--> Jack has 52 x 2 = 104 more cards than Aqil at first.

If Aqil gave Jack 34 cards,
--> Jack would have 104 + 34 x 2 = 172 more cards than Aqil

So, 4u --> 172, 1u --> 43
Number of cards Jack has at first = 7 x 43 - 34 = 267

cheers.

Thank you, MathIzzzFun.

[happyheart]

Jwoofamily:

Use model.


If jack give aqil 52 cards and they have same number means the model is like this.

J [ ][ 52 ][ 52 ]
A [ ]

If A gives 34 to J, the model will be as shown below whereby 34+34+52+52=4 units.

J [][][][34][34][ 52 ][ 52 ]
A [][][]

Find 1 unit and you can find solve the problem by tracing back to the original quantity.

Thank you, Jwoofamily.

[happyheart]

MathIzzzFun:

happyheart:

Hi,

pls help with this question. Thanks!

Andy, Brad, Colin shared money to buya present for their teacher. The ratio of the amount of money contributed by Andy to the total amount contributed by Brad, Colin and Dominic was 1:5. Brad contributed 1/11as much as the total contributed by Dominic. If Andy contributed $2.10 more than Brad, how much did Dominic contribute?

...seems that some info was left out ??

Soorry!! :imsorry: I rechecked the question and it should be phrased like this.


Andy, Brad, Colin shared money to buy a present for their teacher. The ratio of the amount of money contributed by Andy to the total amount contributed by Brad, Colin and Dominic was 1:5. Brad contributed 1/11 as much as the total contributed by Andy, Colin and Dominic. Colin contributed 4/5 of the amount contributed by Dominic. If Andy contributed $2.10 more than Brad, how much did Dominic contribute?

[happyheart]

cimman:

happyheart:

Hi, one more please. I am always confused when there is transfer back and forth.Thanks.


Jack and Aqil had some game cards. If Jack gave Aqil 52 cards, he would have the same number of cards as Aqil. If Aqil gave Jack 34 cards, the ratio of the number of cards Aqil had to the number of cards Jack had would be 3:7.How many cards did Jack have at first?

actually, you should see this as a Double If question rather than a back and forth transfer question. Double If question is easy to recognize because there are 2 Ifs in the question. The key thing to note in Double If question is the starting point (Before) is the same in both If cases. Work your way up to the Before values in both cases (each If statement is a case) and equate them together.

Thanks Cimman. Somehow I cannot see the question like you :scratchhead: I see the question more like one person give something to another and return back to the same person etc. I am lost by the second transfer and cannot draw the model correctly. MathIzzzfun and Tianzhu has kindly showed the way to solve this question.

[MathIzzzFun]

happyheart:

MathIzzzFun:

[quote=\"happyheart\"]Hi,

pls help with this question. Thanks!

Andy, Brad, Colin shared money to buya present for their teacher. The ratio of the amount of money contributed by Andy to the total amount contributed by Brad, Colin and Dominic was 1:5. Brad contributed 1/11as much as the total contributed by Dominic. If Andy contributed $2.10 more than Brad, how much did Dominic contribute?

...seems that some info was left out ??

Soorry!! :imsorry: I rechecked the question and it should be phrased like this.


Andy, Brad, Colin shared money to buy a present for their teacher. The ratio of the amount of money contributed by Andy to the total amount contributed by Brad, Colin and Dominic was 1:5. Brad contributed 1/11 as much as the total contributed by Andy, Colin and Dominic. Colin contributed 4/5 of the amount contributed by Dominic. If Andy contributed $2.10 more than Brad, how much did Dominic contribute?[/quote]Total amount of money remains the same,
Brad : Andy, Colin & Dominic : Total -> 1u : 11u : 12u

Andy : Brad, Colin & Dominic : Total = 1 : 5 : 6 -> 2u : 10u : 12u

Andy : Brad : Total : Colin & Dominic
--> 2u : 1u : 12u : 9u (= 12u - 2u -1u)

Colin : Dominic : Colin & Dominic --> 4u : 5u : 9u

Andy : Brad: Colin : Dominic --> 2u : 1u : 4u : 5u

Andy contributed $2.10 more than Brad,
2u - 1u = 1u --> $2.10

Dominic's contribution --> 5 x $2.10 = $10.50

cheers.

[happyheart]

MathIzzzfun, Thank you for your help.