Q&A - PSLE Math

[lizawa]

Hershey:

Dear Parents, hope someone can help to solve this 2 questions from 2010 Catholic High Prelim paper.


1) At a conference made up of speakers and participants, there were 20% more men than women. the ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.

a) Find the ratio of male speakers to male participants at the conference.

b) Halfway, 40 male participants left the conference and another 60 male participants joined the conference. in the end, there was 3/4 as many male participants as female participants remaining behind. How many speakers were there at the conference.

Hi Hershey,

Maybe something wrong with your part b). Since the net male participants is +20 and at first the ratio was 1 : 1, how can there be 3/4 as many male participants as female partcipants ? Either the question was wrong or copied wrongly.

a) Men : Women = 6 :5
Mspeaker : Fspeaker = 8 : 5
Mpart : Fpart = 1 : 1

Men : Women = 6 :5 = 18 :15
therefore Mpart : Fpart = 1 : 1 = 10: 10
Mspeaker : Mpart = 8 : 10 = 4: 5

[lizawa]

Hershey:

Dear Parents, hope someone can help to solve this 2 questions from 2010 Catholic High Prelim paper.



2. At 9am, John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, John would pass Mary 300m away from the midpoint.

a) what time did they pass each other?

b) If John took another 3 mins to reach Point B, what time would Mary reach Point A?

Really don't understand why kids are being drill on this kind of questions...even adults need to think....

Thanks.

Solution for question 2 :
http://i56.tinypic.com/33m62q1.jpg\">

[MathIzzzFun]

Hershey:

Dear Parents, hope someone can help to solve this 2 questions from 2010 Catholic High Prelim paper.


1) At a conference made up of speakers and participants, there were 20% more men than women. the ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.

a) Find the ratio of male speakers to male participants at the conference.

b) Halfway, 40 male participants left the conference and another 60 male participants joined the conference. in the end, there was 3/4 as many male participants as female participants remaining behind. How many speakers were there at the conference.


2. At 9am, John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, John would pass Mary 300m away from the midpoint.

a) what time did they pass each other?

b) If John took another 3 mins to reach Point B, what time would Mary reach Point A?

Really don't understand why kids are being drill on this kind of questions...even adults need to think....

Thanks.

Hi

For Q1(b), the question should be \"Halfway, 40 male participants left the conference and another 60 female participants joined the conference.\"

http://i52.tinypic.com/280ld0g.jpg\">

cheers.

[MathIzzzFun]

Hershey:

Dear Parents, hope someone can help to solve this 2 questions from 2010 Catholic High Prelim paper.


1) At a conference made up of speakers and participants, there were 20% more men than women. the ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.

a) Find the ratio of male speakers to male participants at the conference.

b) Halfway, 40 male participants left the conference and another 60 male participants joined the conference. in the end, there was 3/4 as many male participants as female participants remaining behind. How many speakers were there at the conference.


2. At 9am, John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, John would pass Mary 300m away from the midpoint.

a) what time did they pass each other?

b) If John took another 3 mins to reach Point B, what time would Mary reach Point A?

Really don't understand why kids are being drill on this kind of questions...even adults need to think....

Thanks.

Hi

For Q1(b), the question should be \"Halfway, 40 male participants left the conference and another 60 female participants joined the conference.\"

http://i52.tinypic.com/280ld0g.jpg\">

For Q2, refer to http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=280&start=3470

cheers.

[MathIzzzFun]

wkong:

Thanks MathIzzzFun

u r welcome

cheers.

[Hershey]

MathIzzzFun:

Hershey:

Dear Parents, hope someone can help to solve this 2 questions from 2010 Catholic High Prelim paper.


1) At a conference made up of speakers and participants, there were 20% more men than women. the ratio of male speakers to female speakers was 8:5. There was an equal number of male and female participants.

a) Find the ratio of male speakers to male participants at the conference.

b) Halfway, 40 male participants left the conference and another 60 male participants joined the conference. in the end, there was 3/4 as many male participants as female participants remaining behind. How many speakers were there at the conference.


2. At 9am, John was cycling from Point A to Point B. At the same time, Mary was cycling from Point B to Point A using the same route as John. Cycling at a speed of 4km/h faster than Mary, John would pass Mary 300m away from the midpoint.

a) what time did they pass each other?

b) If John took another 3 mins to reach Point B, what time would Mary reach Point A?

Really don't understand why kids are being drill on this kind of questions...even adults need to think....

Thanks.

Hi

For Q1(b), the question should be \"Halfway, 40 male participants left the conference and another 60 female participants joined the conference.\"

http://i52.tinypic.com/280ld0g.jpg\">

For Q2, refer to http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=27&t=280&start=3470

cheers.

Thank you so much. Its my typo error on Q1b. :imsorry:

[youngtay]

Hi, please help


A lorry left Town M and travelled towards Town G at an average speed of 80km/h. An hour later, a car left Town M and travelled towards Town G at an average speed of 100km/h.
The car passed Town K, which was halfway between Town M and Town G, 30 minutes earlier than the lorry.
The car reached Town G at 2300 hours.
At what time did the lorry leave Town M for Town G?
TIA

[MathIzzzFun]

youngtay:

Hi, please help


A lorry left Town M and travelled towards Town G at an average speed of 80km/h. An hour later, a car left Town M and travelled towards Town G at an average speed of 100km/h.
The car passed Town K, which was halfway between Town M and Town G, 30 minutes earlier than the lorry.
The car reached Town G at 2300 hours.
At what time did the lorry leave Town M for Town G?
TIA

Hi

2 approaches ..

Using speed ratio & time ratio :

http://i55.tinypic.com/2ex0wzo.jpg\">

Using \"area\" concept - http://www.flickr.com/photos/62167097@N02/5939052277/in/photostream

cheers.

[wkong]

Hi all, have a question for you-


Chef John only has a 3-minute hourglass timer and a 5-minute hourglass timer. Write down a list of instructions to help Chef John time his cooking to exactly 7 minutes.

Thanks in advance.

[stary]

Hi all,


Need help on average.

The pupils in 2 classes, 1A and 1B did a Mathematics test. The average score of class 1A, which had 24 pupils, was 87. The average score of Class 1B was 80. If the average score of the two classes was 83, how many pupils were there in Class 1B?

Ans key says the ans is 32, but I do not know how to get the explanation for the workings...

Can someone explain to me the bold and underlined part?

Total score of class 1A -> 87 x 24 = 2088
83 x 24 = 1992
2088 - 1992 = 96
83 - 80= 3
96 / 3 = 32

Appreciate your assistance.