Q&A - PSLE Math

[tianzhu]

Michaelia0816:

No, I meant that I do not like to use Gc in this type of question, trying to learn other kind of ways.

Hi

Exploring other ways of solving questions will certainly brighten up your days and makes learning more interesting.

Best wishes

[elkniwt]

Hi,


Need help here. From my dd's teacher, units are required in all number statements, not just in the final answer.

e.g To find distance :
80km/h x 2 h = 160 km

Half a mark is deducted when no units is written.

On the contrary, my friend's son from another school is told that if units is given in number statement, marks will be deducted. Units should only be given in the final answer.

So the previous number statement is marked wrong, while the following is correct :
80 x 2 = 160

So, my friend and I are confused when we compare notes. What is correct? Though they are from different schools but they will be taking the same PSLE. Can someone pls advise. Thank you very much.

Another question :
My friend's son did this qn in one of his practice paper and was marked as \"Fluke\". Teacher said that it was fluke cos he wrote units. No marks given.

The qn is :
Harbour City is 420 km away from Salt Lake City. At 8 am, Mr Tan set off from Harbour City to travel to Salt Lake City. At the same time, Mr Lee set from Salt Lake City towards Harbour City at a speed of 70km/h. If they passed each other at 10:30 am, what was the average speed Mr Tan is driving at?

His answer is :
From 8 am to 10:30am -> 2.5 h
420km / 2.5 h = 168 km/h
168 km/h - 70km/h = 98 km/h
Mr Tan is driving at 98 km/h

(Answer is marked as Fluke) :? :?:

[tianzhu]

2DMommy:

Please help me with these two questions :


1) Nigel and Osman started driving from the same point but in opposite directions round a 20-km circular track. Nigel took 10 mins to complete each round. The two drivers met each other along the track 6 mins after setting off.
a) Find Osman's driving speed in km/h
b) How many rounds would each driver have completed when they met each other at the starting point for the second time after setting off in opposite directions ?

Hi

As in any questions on Speed, start with a simple diagram.

Nigel

10 mins ------- 20 km

2 mins -------- 4 km

6 mins ------- 12km

Hence, Osman traveled 8 km (20-12)

6 mins ------ 8 km

60 mins ------ 80 km

Osman’s speed ------ 80 km/h

15 mins ------ 20km

Osman completed one round in 15 minutes.

For the second part, do a listing.

They met for the second time at after 30 minutes.

Nigel ------ 3 rounds

Osman ------- 2 rounds

Alternatively you may find the LCM of 10 and 15 which is 30.

Best wishes

[Michaelia0816]

Thanks!

[Michaelia0816]

Help with this question,


Dawei has $180 and Yawen has $55. After their aunt gave each of them an equal amount of money, Dawei had twice as much money as Yawen. How much money did their aunt give to each of them?

[Shimmer]

Q1.Daniel had 40% more stickers than Brandon. Daniel and Brandon each gave 20%of their stickers to Calvin. As a result ,Calvin stickers increased by 80%. If Daniel has 20 more stickers than Calvin in the end, how many stickers did Brandon have at first?

Q2.At a confererence 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 female 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?

[Michaelia0816]

tianzhu:

Michaelia0816:

Then, how about this, and also not using guess and check,


Each day, Rahman saves $0.90. 6 days after Rahman starts saving, Minah starts saving $0.20 more than Rahman each day. When Minah has saved $4.60 more than Rahman, how much money has Rahman saved?

In this case, the numbers of days is not the same, then what should the statement be?

Hi

This question is quite similar to that of the “catching up” type of speed question.

Starting with a simple diagram helps.

Rahman has a head start of 6 days ------- 6*90 ------- 540 cents

Minah saves 20 cents more than Rahman each day

540 + 460 ------- 1000

1000/20 ------- 50

Minah will save $4.60 more than Rahman in 50 days

50*90 ------- 4500

Rahman ------- 4500+ 540 ------- 5040 ------$50.40

Best wishes

Hi! Tianzhu, pls check, I think it should be $26.10 instead!

[peggy]

Please help.



Nicole received more money than Tricia from their mother. 40% of Tricia’s money is $16 less than 25% of Nicole’s money. If Nicole gives 35% of her money to Tricia, Nicole will have $12 less than Tricia.

A. How much money does Tricia has?
B. How many per cent more money does Nicole has than Tricia at first?
Round off your answers to the nearest 2 decimal places.


Thanks.

[Michaelia0816]

Michaelia0816:

Help with this question,


Dawei has $180 and Yawen has $55. After their aunt gave each of them an equal amount of money, Dawei had twice as much money as Yawen. How much money did their aunt give to each of them?

Need help, need it by today!

[charsen]

Hi


Since the aunt gave each of them them same amount of money,their difference is the same.We call this’Constant Difference’.
In this case,we can solve with that method easily.
Difference between to of them at first-180 -55=125
1Unit-125,as the differnce is constant.
2Unit-125*2=250
Money gave to each of them-250-180=70(ANS)
Cheers