Q&A - PSLE Math

[tianzhu]

Andrew Lee:

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Hi

A:B ------ 4:5 ------- 16:20
B:C ------4:5 --------20:25

Shaded area of A ------- 12 units
Unshaded area of A ------- 4 units

Unshaded area of C ------- 25 - 12 ------13 units

Unshaded area of A/ Unshaded area of C ------- 4/13

Percentage of figure shaded ------- 12/(25+4) -------12/29 ------ 41%

Best wishes

[Winx5015]

Hi tianzhu,


Thanks for your help.

Have a wonderful weekends

[Andrew Lee]

tianzhu:

Andrew Lee:

Q7. Cindy planeed to cycle from Town G to Town H.If she were to cycle at 9km/h, she would reach Town H at 8.45pm. If she were to cycle at 12KM/h, she would reach Town H at 8.15pm.What was the distance between Town G & Town H?


Q16..
A tank with a square bas is 40% filled with water. When 60% of the water is poured out, the height of the water falls by 9.6cm. 120.96 lite of water is poured in to fill the tank to the brim. What is the ratio of the height of the tank to one side of its base ? (simple form)

Hi

Q1)

Speed ratio ------ 3:4 (9:12)
Time ratio ------ 4:3

1 unit ------ ½ h
3 units ------ 1.5h

Distance between G and H ------ 1.5*12 -------18 km

Q2)

40%*60% -------24%
Amount of water left ------- 16%

Volume
84% -------- 120960 cubic cm
100% ------- 144000 cubic cm

Height
24% ------- 9.6cm
100% ------- 40 cm

Area of square base ------ 144000/40 ------- 3600
One side of square base ------- 60

40:60 ------2:3

Best wishes

谢谢你们的帮忙 :rahrah:

[Winx5015]

A question using Draw a Model Method


Alan and Bobby had a certain sum of money. If Alan gave 5/8 of his money to Bobby, he would have $1400 less than Bobby. If Alan has 25% of his money to Bobby, he would have $800 less than Bobby. How much did Alan have?

Thanks!

[tianzhu]

Winx5015:

Hi tianzhu,


Thanks for your help.

Have a wonderful weekends

Hi

Good Morning.

You're welcome.

Have a good weekend too.

Best wishes

[tianzhu]

Andrew Lee:

谢谢你们的帮忙 :rahrah:

Hi

Good Morning.

You're welcome.

Have a good weekend.

Best wishes

[tianzhu]

Winx5015:

A question using Draw a Model Method


Alan and Bobby had a certain sum of money. If Alan gave 5/8 of his money to Bobby, he would have $1400 less than Bobby. If Alan has 25% of his money to Bobby, he would have $800 less than Bobby. How much did Alan have?

Thanks!

Hi

Good Morning.

Yes, you may use MD for this solution. But, I wouldn’t opt to use it.

MD is one of many problem solving heuristics in primary maths syllabus; it’s not the only one.

This may be a neater alternative.

First scenario

Alan ----- 3 units
Bobby ----- 3 units + 1400
Total ----- 6 units + 1400

Second scenario

I think some information is missing in the second condition.I'll take it it read as \"If Alan gave 25% of his money to Bobby\"

Alan ----- 6 units
Bobby ----- 6 units + 1400
Total ----- 12 units + 800

The total amount of money remains the same in both scenarios.

6 units + 1400 ----- 12 units + 800
6 units ------ 600
1 unit ----- 100

Alan ------ 8 units ------- 800

Best wishes

[Winx5015]

Thanks tianzhu:)

[YumYum]

Hi, can anyone pls help with this Qn:


At 2 p.m, Boat A set off from Jolly Pier and travelled towards Hope Pier at a constant speed.

At 2.15 p.m, Boat A had travelled 3/7 of the journey and it overtook Boat B which was travelling along the same route at an average speed of 120 km/hr.

When Boat A reached Hope Pier, Boat B was still 10 km away from Hope Pier.

a) Find the speed at which Boat A travelled.
b) Find the distance between Jolly Pier and Hope Pier.

thank you.

[atutor2001]

YumYum:

Hi, can anyone pls help with this Qn:


At 2 p.m, Boat A set off from Jolly Pier and travelled towards Hope Pier at a constant speed.

At 2.15 p.m, Boat A had travelled 3/7 of the journey and it overtook Boat B which was travelling along the same route at an average speed of 120 km/hr.

When Boat A reached Hope Pier, Boat B was still 10 km away from Hope Pier.

a) Find the speed at which Boat A travelled.
b) Find the distance between Jolly Pier and Hope Pier.
thank you.

Long time no do math. Let me try try.

Divide the journey in 7P

Boat A travelled 3P (i.e. 3/7 of journey) in 1/4 h (2.15 - 2.00 = 15 min)
1P will take 1/12 h
4P will take 4/12 = 1/3h (to finish the remaining journey)

Boat B take the same 1/3h to travel 1/3 x 120 = 40 km
40km + 10km = 50 km will be the distance of 4P

(a) Speed of Boat A = 50 / (1/3) = 150 km/h

(b) Distance between the 2 piers = 7P = 50/4 x 7 =87.5 km