Q&A - PSLE Math

[tianzhu]

Hi


The topic on Speed in PSLE Maths might be intimidating to some students. Speed questions come in different forms and sometimes can be confusing.

This question posted earlier by peggy requires students to understand the relationship between the length of tunnel and the length of the train.

1. At 9.30am, Train One which was 200m long, pulled out of Station X and travelled towards Station Y at a uniform speed of 80km/h. Half an hour later, Train Two which was 150m long, left Town Y and travelled towards Town X at a uniform speed of 90 km/h.

A) How far Train One travelled when Train Two left Station Y?
B) The two trains met each other of the tunnel. Both trains took 15mins to completely come out of the tunnel. Calculate the length of the tunnel.

I’ll use an earlier question in this thread as an illustration. The question may be tweaked by using bridge, platform instead of tunnel.

A 200m long MRT train took 20 min to pass through a tunnel completely. If the MRT train travelled at an average speed of 120m/min, find the length of the tunnel.

I hope current PSLE students will find it useful.

Best wishes

http://farm8.staticflickr.com/7081/7016655239_71c7e54c20_z.jpg\">

[jtparent]

Hi,


Pse assist.

Question: I have 38 notes in my wallet. Some of them are $10 notes. The rest are $2 notes. The total value of these notes is $228.
A) how many $10 notes are there in my wallet?
B) find the difference between the total value of the $10 and $2 notes.

TIA

[YumYum]

Hi, can anyone pls help with this Qn:


thanks http://i40.tinypic.com/vxzvbl.jpg\">

[YumYum]

Hi, need help with this one as well: http://i43.tinypic.com/2wmi8hd.jpg\">

[Symum]

Hi,

Please help!
Lincoln spent $95 of his pocket every month and saved the rest. This month, he decided to spend only $75, thereby increasing his savings by 40%.
(a) What was his pocket money every month?
(b) Find the ratio of his expenditure to his savings for this month.

Karen, Nora and Sakina baked a total of 280 tarts. Karen baked 1/4 as many tarts as Nora. Nora baked 4/5 as many tarts as Sakina. What percentage of the total number of tarts did Nora bake?

At city hall station, there were 360 commuters on an Mrt train. There were 20% more children than men and 20% fewer women than men on the train. 120 more commuters boarded the train at the next station. The number of women increased by 50% and the number of children increased by 25%. What was the percentage increase in the number of men?

Thanks

[MathIzzzFun]

jtparent:

Hi,


Pse assist.

Question: I have 38 notes in my wallet. Some of them are $10 notes. The rest are $2 notes. The total value of these notes is $228.
A) how many $10 notes are there in my wallet?
B) find the difference between the total value of the $10 and $2 notes.

TIA

Hi

using area model...

http://i43.tinypic.com/33n9lsp.jpg\">

cheers.

[MathIzzzFun]

YumYum:

Hi, can anyone pls help with this Qn:


thanks http://i40.tinypic.com/vxzvbl.jpg\">

Hi

area ADF --> 2u
area CDF --> 4u
area CFA --> 6u
area CFB = area CFA
area CFB --> 6u
area CDB --> 4u + 6u = 10u
area ADB --> 1/2 x 10u = 5u
area AFE = area BFE --> (5u-2u)/2 = 1.5u
area ADFE --> 3.5u
so, 3.5u --> 35 cm2, 1u --> 10 cm2
total area ABC --> 15u --> 150 cm2

cheers.

cheers.

[MathIzzzFun]

YumYum:

Hi, need help with this one as well: http://i43.tinypic.com/2wmi8hd.jpg\">

Hi

shaded area = area of semi-circle --> to visualize this - try to duplicate the circles so that you get a \"6-petal flower\" in the centre circle

cheers.

[MathIzzzFun]

Symum:

Hi,

Please help!
Lincoln spent $95 of his pocket every month and saved the rest. This month, he decided to spend only $75, thereby increasing his savings by 40%.
(a) What was his pocket money every month?
(b) Find the ratio of his expenditure to his savings for this month.

Thanks

Hi

Increase in savings --> $20
40% of savings --> $20
140% of savings --> $70

a) Pocket money = $75 + $70 = $ 145
b) ratio of expenditure to savings for this month = 75 : 70 = 15 : 14

cheers.

[MathIzzzFun]

Symum:

Hi,



Karen, Nora and Sakina baked a total of 280 tarts. Karen baked 1/4 as many tarts as Nora. Nora baked 4/5 as many tarts as Sakina. What percentage of the total number of tarts did Nora bake?


Thanks

Hi

Karen --> 1 unit
Nora --> 4 units
Sakina --> 5 units
Total 10 units

4/10 x 100% = 40%
Nora baked 40% of the tarts.

cheers.