Q&A - PSLE Math

[Dharma]

firebird:

Dear Dharma


Good evening.

First I have to tell you that i sincerely appreciate your help.

I am unable to follow your working (posted on 23 June 2010 for my doubts) for Question 1 rasied by me. This question refers to Melvin, Tomas and Jack taking out coins from piggy bank.

My doubts are:
1) How many biggy banks are there.
2) Why 4/5 X 795 = 636
And then 795 - 636 = 159

What I worked out from the solution given by you as I was totally lost before was this:
Let Thomas be T, Melvin be M, Jack be J

Given T + J = 795
Given M + T = 5/13
Given J + M = 4/5

So J + T = 2 - 5/13 - 4/5 = 52/65
53u = 795
u = 15

Then J - M = (J+T) - (J+M) = 53/65 - 4/5
= 53/65 - 52/65
= 795 - 780(52x15)
= 15

What i am getting is 15.

I know i am wrong.

Please guide me. New or addtional method to derive a solution is most welcome.

Thank you.
Firebird

Hi firebird,

Your answer is correct. I'm sorry abt the careless mistake and thanks for pointing it out and now have amended the solution.

Q1)
Melvin & Thomas => 5/13
Jack & Melvin => 4/5
Jack & Thomas = > 2 – 5/13 – 4/5 = 53/65
53u = 795
1u = 15

Diff = 53u – 52u = 1u = 15 (Thomas took out Melvin 15 more coins than Melvin)

[firebird]

Dear Dharma


Good morning.

Many thanks for your answer.

Your help is very much appreciated.

With best regards
firebird

[Tang]

firebird:

1) Melvin, Thomas and Jack put some coins in a piggy bank. They wanted to donate some money to the charity, so Thomas and Jack took out 795 coins. Melvin and Thomas took out 5/13 of the coins from their piggy bank. Jack and Melvin took out 4/5 of the coins from their piggy bank. How many more coins did Thomas take than Melvin?

T + J --> 795 coins

M + T --> 5/13 = 25/65

M + J --> 4/5 = 52/65

2 M + T + J --> 25/65 + 52/65 = 77/65

1 M --> 77/65 - 65/65 = 12/65 (since M + T + J = 1 = 65/65)

2 M --> 12/65 x 2 = 24/65

T --> 25/65 - 12/65 = 13/65

T - M --> 13/65 - 12/65 = 1/65

T + J --> 77/65 - 24/65 = 53/65

53 u --> 795 coins

1 u --> 795/53 = 15 coins

Thomas took 15 more coins than Melvin.

[liketoeat]

[/quote]


Anytime! (BTW, your moniker makes me hungry! :))[/quote]


yours too, muffins, yumyum

[Muffins]

liketoeat:

Muffins:

Anytime! (BTW, your moniker makes me hungry! :))

yours too, muffins, yumyum

You'd be the perfect host of the \"How to cook nice meals\" thing in \"Foodies Paradise\"!

[Tang]

Muffins:

liketoeat:

[quote=\"Muffins\"]
Anytime! (BTW, your moniker makes me hungry! :))

yours too, muffins, yumyum

You'd be the perfect host of the \"How to cook nice meals\" thing in \"Foodies Paradise\"! :)[/quote]
Hello,

I got 'A1' for Home Economics. I love to cook. I also like to eat. I need to watch my weight closely.

[corneyAmber]

Tang:

Hello,

I got 'A1' for Home Economics. I love to cook. I also like to eat. I need to watch my weight closely.

Tang is boy or girl??

[abc_parent]

Hi gurus


I remember posting but cannot locate my post anymore.
I just cannot recall where I post them.

So I am re-posting. Hope you all don’t mind.


Q14) If Ahmad and Ben work together, they can complete a job in 12 days. If Ahmad and Ben worked together for 3 days, followed by Ben who worked alone for the next 5 days, they can finish 5/12 of the job. How many days will each of them need to complete the job if they were to work alone?

Given answers:
Ahmad = 20days
Ben = 30days


Q15) Tommy and Wilson jog on a hexagon track (6 equal sides) at 8am. Tommy starts at point C while Wilson starts at point F. Both jog in the direction as shown by the arrows. Tommy’s speed is 1.5 times Wilson’s.
(a) At which point will they meet?
(b) If they meet at 8.20am ,find Tommy’s speed?

[Vanilla Cake]

abc_parent:

Q14) If Ahmad and Ben work together, they can complete a job in 12 days. If Ahmad and Ben worked together for 3 days, followed by Ben who worked alone for the next 5 days, they can finish 5/12 of the job. How many days will each of them need to complete the job if they were to work alone?

See http://www.kiasuparents.com/kiasu/forum/viewtopic.php?t=280&postdays=0&postorder=asc&start=1380, Dharma's solution dated 20 Jun 2010 08:42 and Uncle Tianzhu's solution dated 20 Jun 2010 09:25

abc_parent:

Q15) Tommy and Wilson jog on a hexagon track (6 equal sides) at 8am. Tommy starts at point C while Wilson starts at point F. Both jog in the direction as shown by the arrows. Tommy's speed is 1.5 times Wilson's.
(a) At which point will they meet?
(b) If they meet at 8.20am ,find Tommy's speed?

See http://www.kiasuparents.com/kiasu/forum/viewtopic.php?p=178599#178599 dated 06 May 2010 22:51 and CoffeeCat's solution dated 06 May 2010 23:00

[abc_parent]

Thanks to ksi , Dharma , Uncle Tianzhu, VanillaCake & CoffeeCat!!!