Tutor MathsGuru: Ask me for your burning Maths questions!

[tianzhu]

Almighty:

Hi Tianzhu,
I had worded exactly as how it was in my source. Sorry to reply late.Just saw yr quote.
Thankyou Dharma n tianzhu 4 the g8t help...

Hi Almighty
Good Morning

No worries.
Enjoy your PSLE journey.

Best wishes

[Vanilla Cake]

Carrot:

hi

tough question here pleasee help

john shifted the decimal point onumber twice to the left to obtain a new number. the difference between thr new number and the original number was 136.62
a) How many times of the new number is the original number?
b) What is the sum of the 2 numbers ? :scratchhead: :stupid:

This is a http://road-to-psle.blogspot.com/2010/08/rgs-primary-2009-psle-math-prelim-paper_3183.html set on 26 August 2009.
It's good to state the source and level of the question posted as well as the given answer to help potential problem solvers in one way or another.

[Carrot]

tianzhu:

Tang:

Hi,
Maths6a's answers are correct.
139.38 is the sum of the 2 numbers --- that is 101 units
and not the original number or 100 units.

Hi Tang
Good Morning

Yes, the correct answer is 139.38.

I am sorry for the mistake.

Best wishes

err hi guys , Pardon if you can repharse your working and give me your answer.How you get yr 138??? :? :?

[tianzhu]

Carrot:

err hi guys , Pardon if you can repharse your working and give me your answer.How you get yr 138??? :? :?

Hi

Please ignore my earlier post; I misread the question as asking for the original number.

The question asks for the sum of the original and new number.

The original number is 138.
The new number is 1.38
Therefore the sum of two numbers is 139.38.

Best wishes

[Carrot]

tianzhu:

Carrot:

err hi guys , Pardon if you can repharse your working and give me your answer.How you get yr 138??? :? :?

Hi

Please ignore my earlier post; I misread the question as asking for the original number.

The question asks for the sum of the original and new number.

The original number is 138.
The new number is 1.38
Therefore the sum of two numbers is 139.38.

Best wishes

Thanks for all help :celebrate:

[Herbie]

I have 2 qns,


a. For every $2 that Edyy spent, Fred spent $3. After Eddy had spent all his money. Fred still had 3/8 of the total amount of the two boys had at first.

What fraction of the total amount of money did Eddy have at first?
What was the ratio of Fred’s money to Eddy’s money at first?

b. Mr Lee Left Town M and travelled towards Town N at an average speed of 80km/h. An hour later, mr ong left Town M and travelled towards Town N at an average speed of 100km/h. mr Ong passed Town Q which was halfway between Town M and Town N 30 minutes earlier than Mr Lee. If Mr Ng reached Town N at 10pm, at what time did Mr Lee leave Town M for Town N?


TIA.

[Herbie]

Hi Dharma can help with the speed qn below:


A van travelled from town A to town B at an average spped of 55km/h. A car started its journey from Town B to town A at the same time as the van, travelling at an average speed of 90km/h. The two vehicles passed each other 70km from the middle of the whole journey. Find the distance between the two towns.

TIA

[Dharma]

Herbie:

Hi Dharma can help with the speed qn below:


A van travelled from town A to town B at an average spped of 55km/h. A car started its journey from Town B to town A at the same time as the van, travelling at an average speed of 90km/h. The two vehicles passed each other 70km from the middle of the whole journey. Find the distance between the two towns.

TIA

Speed ratio => Van : Car = 11 : 18

When time is fixed ( when they meet)

Distance ratio => Van : Car = 11 : 18
18u - 11u = 7u
7u = 70km x 2 = 140km
1u = 20km
Distance betwen the towns = 29u = 29 x 20km =580km

[Vanilla Cake]

Herbie:

I have 2 qns,

Hi Herbie,
While waiting for Uncle Dharma's solutions, pls see whether my solutions are of any help or not?
Thks.

Herbie:

a. For every $2 that Edyy spent, Fred spent $3. After Eddy had spent all his money. Fred still had 3/8 of the total amount of the two boys had at first.
What fraction of the total amount of money did Eddy have at first?
What was the ratio of Fred's money to Eddy's money at first?

This is a 5-mark question from Rulang Primary School P6 Prelim 2009 paper 2 Q17

E: [s][s]
F: [s][s][s][][][]

Note: [s]-Money spent.

2/8=1/4
(a) Fraction of the total amount of money that Eddy had at first = 1/4.

From the model drawing:
6:2
3:1
(b) Ratio of Fred's money to Eddy's money at first = 3:1

Herbie:

b. Mr Lee Left Town M and travelled towards Town N at an average speed of 80km/h. An hour later, mr ong left Town M and travelled towards Town N at an average speed of 100km/h. mr Ong passed Town Q which was halfway between Town M and Town N 30 minutes earlier than Mr Lee. If Mr Ng reached Town N at 10pm, at what time did Mr Lee leave Town M for Town N?

This is a 4-mark question from Rulang Primary School P6 Prelim 2009 paper 2 Q11
From Town M to Town Q, Mr Ong took 1 h+1/2h = 1 and 1/2 h less time than Mr Lee.
Since Town Q was the mid-point, Mr Ong took 1.5 hx2 = 3 h less time than Mr Lee to travel from Town M to Town N.

Ratio of speed
Mr Ong : Mr Lee
100 : 80
5 : 4

Ratio of time
Mr Ong : Mr Lee
4 : 5

Difference in the ratio of time = (5-4)units = 1 unit -> 3 hours
Mr Ong took 4 units which was equal to 4x3 hours = 12 hours
Since Mr Ong reached Town N at 10 p.m., he left Town M at 10 a.m.
So, Mr Lee Left Town M at 9 a.m. for Town N.

[Dharma]

Herbie:

I have 2 qns,


a. For every $2 that Edyy spent, Fred spent $3. After Eddy had spent all his money. Fred still had 3/8 of the total amount of the two boys had at first.

What fraction of the total amount of money did Eddy have at first?
What was the ratio of Fred's money to Eddy's money at first?

b. Mr Lee Left Town M and travelled towards Town N at an average speed of 80km/h. An hour later, mr ong left Town M and travelled towards Town N at an average speed of 100km/h. mr Ong passed Town Q which was halfway between Town M and Town N 30 minutes earlier than Mr Lee. If Mr Ng reached Town N at 10pm, at what time did Mr Lee leave Town M for Town N?


TIA.

Q1
The amount of money Eddy and Fred had at first ( N = no. of days Eddy to spend all his money)
Eddy : $2N
Fred : $3N + $3N = $6N ( $3N is the amount Fred had left; so fraction Fred had left = 3/(6 + 2) = 3/8 )

a)\tFraction of total amt Eddy had at first = 2/ (2 + 6) = ¼
b)\tRatio = 6 : 2 = 3: 1

Q2
When Ong left Town M, Lee had already travelled 80km (80km/h x 1 hr)
Time taken to overtake = 80km/(100km/hr – 80km/hr) = 4 hrs
From overtaking point to the midpoint of both towns; distance is constant(fixed)

Speed ratio => Lee : Ong = 4 : 5
Time ratio => Lee : Ong = 5 : 4
5u – 4u = 1u = ½ hr
Time taken by Ong = 4u = 2 hrs
Time taken by Ong to travel from Town M to Town N = (4 + 2)hrs x 2 = 12 hrs
Ong left Town M at 10am (12 hrs before 10pm)
So, Lee left Town M at 9am (1 hr before Ong)