Tutor MathsGuru: Ask me for your burning Maths questions!

[Guan Hui]

After spending 2/5 of his money on markers, he left with 3/5 of his money left. He then spend 1/3 of the remainder on a highlighter.

So..
1/3 * 3/5= 1/5
so he actually spend 1/5 of his money on the highlighter.
Since we know he spend $0.90 on highlighter, we know the amount he spend on markers is $0.90 x 2=$1.80

Does this clear the question?

[sachiko]

Guan Hui:

After spending 2/5 of his money on markers, he left with 3/5 of his money left. He then spend 1/3 of the remainder on a highlighter.

So..
1/3 * 3/5= 1/5
so he actually spend 1/5 of his money on the highlighter.
Since we know he spend $0.90 on highlighter, we know the amount he spend on markers is $0.90 x 2=$1.80

Does this clear the question?

Yes, it is very clear. Thanks so much.

[pandan]

Hi,


I am not able to open the solutions provided by mathsguru and the other parents. Is it something wrong with my pc ? Please help me.

Thank you.

[pandan]

Hi again,


I desperately needed those model solutions provided by all the helpful parents. I am having a really hard time helping my girl with her maths paper. Please help me !!

When I click on the picture, it shows a cross. If I save it as "save picture as" I am not able to see it clearly at all. I only encounter this problem today.

Would appreciate your help. Thank you.

[Vanilla Cake]

starlight1968sg:

1) Andy, Betty, Candy and Danny each have some money. The amount of money Andy has is 1/3 of the total amount of money Betty, Candy and Danny have. The amount of money Betty has is 1/4 of the total amount of money Andy, Candy and Danny have. The amount of money Candy has is 1/5 of the total amount of money Andy, Betty and Danny have. If Danny has $1725, how much do they have altogether?

This is Q17 [5 marks] from http://www.orlesson.org/orp/09Ma/2009-Math-SA1-MahaBodhi.pdf set on 5 May 2009.

starlight1968sg:

2) Tom and Jerry each has some money. If Tom spends $90 per day and Jerry spends $45 per day, Tom will have $1100 left when Jerry has spent all his money. If Tom spends $45 each day and Jerry spends $90 each day, Tom will have $1700 left when Jerry has spent all his money. How much did Jerry have?

This is Q16 [5 marks] from http://www.orlesson.org/orp/09Ma/2009-Math-SA1-MahaBodhi.pdf set on 5 May 2009.
This is similar to a 4-mark question from http://www.wendykoh.com/08/primary6-acssa2-maths.pdf set on 20 Aug 2008.

[pandan]

Hi all,


My problem is somehow solved after I rebooted my pc. thank you.

[Tang]

sachiko:

2. A highlighter costs 3 times as much as a marker. Bert spent 2/5 of his money on markers and 1/3 of the remainder on a pen. The highlighter cost $0.90. How many markers did he buy?


Thank you.

1 - 2/5 = 3/5

1/3 x 3/5 = 1/5

3/5 - 1/5 = 2/5

2 u --> $0.90

1 highlighter --> $0.90

1 marker --> 1/3 x 0.90 = $0.30

0.90/0.30 = 3 markers

He bought 3 markers.

[firebird]

Dear mathsguru


Good morning.

Please help me on the following maths:

1) A man travels from Town X to Town Y at 4 Km/h and from Town Y to Town X at 6 Km/h via the same route. The whole journey takes 45 minutes. Find the distance from Town X to Town Y.

Given answer 1.8 Km, however my answer is 1.875 km.

2) A pen costs 40 cents more than a ruler. John paid $x for a pen and a ruler. Find the cost of a ruler in cents.

Given answer is (50-20)cents

3) A Spaceship lego set cost $80 more than a Tommy train set at a toyshop. During its anniversar, a storewide 20% discount was given to all customers. In addition, members of the toyshop enjoy an addtional 10% discount. Mr. Tan, a member of the toyshop, paid a total of $345.60 for the Spaceship lego set and the Tommy train set. Calculate the original price of the Spaceship set.

Given answer is $28

4) Mr. Tan took 6 hours to drive from Town A to Town B.
Mr. Lim, who started at the same time as Mr. Tan, took 4 hours to drive from Town B to Town A. When they meet each other, they were 48 km from the midpoint of Town A and Town B.
(a) Calculate the distance between Town A and Town B.
(b) Calculate the speed of Mr. Tan.

5) 20% of John’s saving is $120 more than 30% of Brian’s savings. After John spent 5/6 of his savings and Brian spent 1/2 of his savings, John has $20 more than Brian. Find the saving of John at first.

Many thanks
firebird

[Vanilla Cake]

Hi firebird,

All your 5 questions are taken from Catholic High School 2009 Primary 6 Preliminary Examination 3 Maths set on 26 August 2009.

firebird:

1) A man travels from Town X to Town Y at 4 Km/h and from Town Y to Town X at 6 Km/h via the same route. The whole journey takes 45 minutes. Find the distance from Town X to Town Y.

This is a 2-mark question from Q30 - paper 1.
Concept - For constant/fixed/same distance, speed is inversely proportional to time.

Ratio of speed
4 : 6

Ratio of time
6 : 4

Total time = 45 min = 0.75 h
(6+4)units = 10 units
10 units = 0.75 h
1 unit = 0.075 h

Time taken for the man to travel from Town X to Town Y at 4 km/h = 6 units x 0.075 h = 0.45 h
Distance from Town X to Town Y = 0.45 h x 4 km/h = 1.8 km

firebird:

2) A pen costs 40 cents more than a ruler. John paid $x for a pen and a ruler. Find the cost of a ruler in cents.

This is a 2-mark question from Q1 - paper 2.
$x = 100x cents
Ruler -> u
Pen -> u + 40 cents
Total cost of a pen and a ruler = 100x cents
Cost of a ruler = (100x-40)cents÷2 = (50x-20) cents

firebird:

3) A Spaceship lego set cost $80 more than a Tommy train set at a toyshop. During its anniversar, a storewide 20% discount was given to all customers. In addition, members of the toyshop enjoy an addtional 10% discount. Mr. Tan, a member of the toyshop, paid a total of $345.60 for the Spaceship lego set and the Tommy train set. Calculate the original price of the Spaceship set.

This is a 5-mark question from Q16 - paper 2.
Spaceship Lego Set -> SL
Tommy train -> TT

SL = 100%+$80
TT = 100%

For members only:
SL = [80/100x(100%+80)]x90/100
= (80%+64)x90/100
= 72% + $57.60

TT = (80/100x100%)x90/100
= 72%

72%+72%+$57.60 = $345.60
144% = $288
1% = $2

100% = $200
$(200+80) = $280

Original price of the Spaceship Lego set was $280

[Vanilla Cake]

firebird:

4) Mr. Tan took 6 hours to drive from Town A to Town B.

Mr. Lim, who started at the same time as Mr. Tan, took 4 hours to drive from Town B to Town A. When they meet each other, they were 48 km from the midpoint of Town A and Town B.
(a) Calculate the distance between Town A and Town B.
(b) Calculate the speed of Mr. Tan.

This is a 5-mark question from Q17 - paper 2 from Catholic High School 2009 P6 Prelim Exam 3 set on 26 August 2009.

Ratio of time
Mr Tan : Mr Lim
6 : 4

Ratio of distance
Mr Tan : Mr Lim
4 : 6

Distance from Town A to midpoint for Mr Tan -> 4 units + 48 km
which was the same as distance from midpoint to Town B for him.
At the point where both met @ 48 km away from midpoint, Mr Lim had travelled 6 units.

6 units = 48km + 48km + 4 units
2 units = 96 km
1 unit = 48 km

Total distance = (4+6) units = 10 units
10 units = 48x10 = 480 km

(a) Distance between Town A and Town B was 480 km

(b) Speed of Mr Tan = 480 km÷6 hours = 80 km/h

Pls refer to this http://prischoolmaths.blogspot.com/2009/06/maths-speed_4616.html for clear understanding which has the same concept. This is ACS(J)/ACS(P)2008 P6 Prelim Q43.