Q&A - PSLE Math

[anneshirleygilbert]

Hello tianzhu,


Please help. I have trouble interpreting the question. As such, am unable to follow your working.

Q2. CYTHNIA walked to the library from school and at the same time, Mrs Lee walked to school from the library. If they walked towards each other, they would meet 4mins later. If they walked in the same direction, (this is after they met, having walked in opposition directions? or they walk from where they were at first?) it would take CYTHNIA 20 mins to catch up with Mrs Lee whose walking speed was 40m/min . How far was the library from the school ? Assume that Mrs Lee’s walking speed was constant at all times.



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

In 20 minutes, Mrs Lee covered 2040 or 800 m

In 4 minutes, Mrs Lee covered 440 or 160 m

In 16 minutes, CYTHNIA covered 960 m (800+160)

In 4 minutes, CYTHNIA covered 240 m (960/4)

Distance between library and school ------- 400 m (240+160)

Please help.

[tianzhu]

anneshirleygilbert:

Hello tianzhu,


Please help. I have trouble interpreting the question. As such, am unable to follow your working.

Hi

It helps to have some sort of visual sketch.

I'll PM to you probably in the evening or tomorrow morning.

Best wishes

[MathIzzzFun]

Shimmer:

Need help on these two speed question !


Q2. CYTHNIA walked to the library from school and at the same time, Mrs Lee walked to school from the library. If they walked towards each other, they would meet 4mins later. If they walked in the same direction, it would take CYTHNIA 20 mins to catch up with Mrs Lee whose walking speed was 40m/min . How far was the library from the school ? Assume that Mrs Lee's walking speed was constant at all times.

Hi

alternate approach...

Distance between school & library --> 1 unit

In 4 min, total distance covered by both Cythnia & Mrs Lee = 1 unit
In 20 min, total distance covered by both Cythnia & Mrs Lee = 5 units
In 20 min,
distance covered by Mrs Lee = 20 x 40 = 800m
distance covered by Cythnia = 1 unit + 800 m
Total --> 1 unit + 1600m = 5 units
1 unit --> 400 m

Distance between school & library = 400m

cheers.

[ozora]

tianzhu:

ozora:

2.the number of marbles in Box A was twice the number of marbles in Box B.
30% of the marbles in Box A and 20% of the marbles in Box B were moved to Box C. As a result, the number of marbles in Box C was increased by 40%. How many marbles were in Box B at first if there are 28 marbles in Box C now?

Hi

Box A: BoxB ------- 2:1 ------- 10:5

30% of the marbles in Box A and 20% of the marbles in Box B were moved to Box C. As a result, the number of marbles in Box C was increased by 40%.

3 units from Box A and 1 unit from Box B moved to Box C.

Box C ------- 14 units

14 units ------ 28

1 unit ------ 2

Box B ------ 5 units ------- 10

Best wishes

thanks tianzhu. the confusion is on the 40%. it cleared my doubts

[susutoo]

tianzhu:

susutoo:

Hi, need help

1) Rita, Siva and Tara planned to share the cost of a present for their friend equally. When buying the present, Siva Tara were short of $26 altogethe. After rita paid for their share, the present was shared by Rita, Siva and
Tara in the ratio of 9:2:1 respectively. how mucn did the present cost?

Hi

Hope this helps.

Best wishes

http://farm8.staticflickr.com/7139/7674265994_d0a1a50748_z.jpg\">

Hi tian zhu,
Thank you :salute:

[Michaelia0816]

Help with this question,


Websites:
http://t.co/ESDuWB7n
http://t.co/gDAem2xk

[Spongy]

Hi, I need help in this question, thank you!

1. There are 4 cyclists, Alan, Bob, Cathy and Dan. Alan, Bob and Cathy started at the same point to overtake Dan, who was a distance ahead of them. Alan took 10h to overtake Dan and Bob took 2h to overtake Dan. The speed for Alan, Bob and Cathy are 4km/h, 5km/h and 10km/h as accordingly. What was the time taken by Cathy to overtake Dan?

[tianzhu]

Michaelia0816:

Help with this question,


Websites:
http://t.co/ESDuWB7n
http://t.co/gDAem2xk

Hi girl

Where are these questions from?

For Q1, area of unpainted surface per cube ------150/6 ------ 25

Each side of cube ------ 5cm

Volume of each cube ------ 125 cubic cm

For Q2,use different colours to differentiate the lines.

There are 5 colour codes.

So, perimeter ------ 15*5 ------75cm

Best wishes

[Michaelia0816]

Thx, Tianzhu, it is from PSLE Booklet, which my HW.

[superhappy]

Michaelia0816:

Thx, Tianzhu, it is from PSLE Booklet, which my HW.

Hi, I need help on this question.

A rectangular tank was filled with water flowing from the tap.
At 10am, the tank was empty.
At 1pm, the tank was 1/3 filled with water.
At what time would the tank be 7/12 filled with water flowing from the tap.

Thank you