Q&A - PSLE Math

Academic support for Primary 6 and PSLE
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suku
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Re: Q&A - PSLE Math

Post by suku » Mon Aug 18, 2014 10:57 pm

vsk wrote:Please help to solve this. Thanks.
Image
From 2nd to 3rd level the height increase = 35 - 26 = 9
The height of 1st level = 26 - 9 =17
To reach height of 89 cm the levels needed = (89 - 17 )/9 + 1
(since each height increase by 9 cm)
= 8 + 1 = 9
(a) He need 9 levels to reach 89 cm
(b) Observing the base, for 2 level he has 2 solid as base, for 3 levels he has 3 solid, so for 9 levels, he need = 9+8+7+6+5+4+3+2+1
= 45 solids

Kangkangteo
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Re: Q&A - PSLE Math

Post by Kangkangteo » Tue Aug 19, 2014 7:51 am

Post subject: Re: Q&A - PSLE MathPosted: Mon Aug 18, 2014

Kangkangteo wrote:
htn wrote:
Hi, anyone has Nanhua 2012 SA2 test paper Q 16.
Can help me upload the picture and teach me how to solve it.

TIA


It is a quadrant - a triangle

1/4 x 22/7 x 28 x 28 = 616

28/2 = 14

1/2 x 28 x 14 = 392

616 - 392 = 224 sq cm


I believe that it should be 1/2 x 28 x 28(instead of 14) =392.


Yes, it should be 1/2 x 28 x 28

MathIzzzFun
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Re: Q&A - PSLE Math

Post by MathIzzzFun » Tue Aug 19, 2014 8:18 am

ILLUSDUCA wrote:
Kangkangteo wrote: Note: For each piece of remaining wood there are 6 surfaces.
Hello Kangkangteo,

Image

For P6, i've seen questions asking for surface area of a cube but not for a cuboid (wooden plank). Even though it is not that hard, I believe that the question is intended to ask for the top area.

Thanks
surface area is not top area only.. surface area refers to exposed area or for ease of understanding-> area that can be painted...
kangkangteo's revised solution for the question is correct.
a) 10 469 cm³
b) 1552 cm² (if there are two pieces of wood remaining) or 1532 cm² (if only one L-shape piece is remaining).

cheers.

PollutedS
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Re: Q&A - PSLE Math

Post by PollutedS » Tue Aug 19, 2014 3:40 pm

Hi, please help with these questions! Thanks!

1) Chun and Devi started jogging from the same place in opposite directions along a straight path. They jogged for 40mins. At the end of the jog, they were 7km apart. Chun's average speed was 6km/h.
What was Devi's average speed?

2) Mei and Lin took part in a cycling race. Mei cycled at a speed of 20km/h. Both of them did not change their speed throughout the race. When Lin covered 1/2 the distance, Mei was 3.5km in front of her. Mei reached the finishing line at 10.45a.m.
What time did Lin reach the finishing line?

PollutedS
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Re: Q&A - PSLE Math

Post by PollutedS » Tue Aug 19, 2014 3:53 pm

I need help again! :)

1) Faizal and Gary ran in a race. When Gary had completed the race, Faizal had only run 5/8 of the distance. Gary's speed was 75km/h faster than Faizal's speed. Both of them did not change their speeds throughout the race.
What was Faizal's speed in m/min?

2) Sharon and Xinyi started cycling at the same time along a 4.5km track. Both did not change their speeds from start to finish. Sharon cycled at 375m/min. When she reached the end of the track, Xinyi was 600m behind her.
What was Xinyi's cycling speed in m/min?


snowball
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Re: Q&A - PSLE Math

Post by snowball » Tue Aug 19, 2014 4:12 pm

Jay spent $20 of his allowance and saved the rest. After increasing his savings by 15%, his spending decreased by 30%. How much was Jay's allowance?

adribaby
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Re: Q&A - PSLE Math

Post by adribaby » Tue Aug 19, 2014 4:37 pm

Image

Pls help. TIA!

tanxexy
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Re: Q&A - PSLE Math

Post by tanxexy » Tue Aug 19, 2014 6:01 pm

PollutedS wrote:I need help again! :)

1) Faizal and Gary ran in a race. When Gary had completed the race, Faizal had only run 5/8 of the distance. Gary's speed was 75km/h faster than Faizal's speed. Both of them did not change their speeds throughout the race.
What was Faizal's speed in m/min?

2) Sharon and Xinyi started cycling at the same time along a 4.5km track. Both did not change their speeds from start to finish. Sharon cycled at 375m/min. When she reached the end of the track, Xinyi was 600m behind her.
What was Xinyi's cycling speed in m/min?
Hi,

Q1) 75km/h = 75x1000/60 = 1250m/min
=> Every minute, Gary gained a distance of 1250m from Faizal.

For every 8 parts Gary ran, Faizal ran only 5 parts
=> Faizal will be 3 parts behind
=> 1250 = 3 parts

Faizal's speed was = 1250/3 * 5 = 2083 1/3 m/min.

Note: The above answer is not realistic as running 2083 m/min is equivalent to running ~34m/s and the world record is only ~11m/s :smile:

So assuming the unit provided was wrong, 75km/h should be 75m/min.

So Faizal's speed would be = 75/3 * 5 = 125 m/min (rather slow but both of them could be just young kids :lol: )

Q2) Time taken by Sharon to complete the track = 4500/375 = 12 min
=> She took 12 min to gain 600 m ahead of Xinyi
=> In 1 min, she gained 600/12 = 50 m
=> Sharon is 50m/min faster than Xinyi
=> Xinyi's speed is 375-325 = 50 m/min.

Hope it helps!

cheers...
Last edited by tanxexy on Wed Aug 20, 2014 10:38 am, edited 1 time in total.

2cor41618
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Re: Q&A - PSLE Math

Post by 2cor41618 » Tue Aug 19, 2014 6:12 pm

PollutedS wrote:Hi, please help with these questions! Thanks!

1) Chun and Devi started jogging from the same place in opposite directions along a straight path. They jogged for 40mins. At the end of the jog, they were 7km apart. Chun's average speed was 6km/h.
What was Devi's average speed?

2) Mei and Lin took part in a cycling race. Mei cycled at a speed of 20km/h. Both of them did not change their speed throughout the race. When Lin covered 1/2 the distance, Mei was 3.5km in front of her. Mei reached the finishing line at 10.45a.m.
What time did Lin reach the finishing line?

1) Dist. covered by Chun---> 40/60 x 6 = 4
Dist. covered by Devi ---> 7 - 4 = 3
Devi's speed --> 3 divide by 40/60 = 4.5

Ans: 4.5 km/h

2) Assume that Mei continue to run after reaching the finishing point, she would be 3.5 km x 2 = 7 km ahead of Lin.
Time taken --> 7/20 h = 21 min
21 min after 10.45 am is 11.06 am

Ans: 11.06 am

tanxexy
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Re: Q&A - PSLE Math

Post by tanxexy » Tue Aug 19, 2014 6:14 pm

snowball wrote:Jay spent $20 of his allowance and saved the rest. After increasing his savings by 15%, his spending decreased by 30%. How much was Jay's allowance?
Hi,
Spending decreased by 30% => 0.3 * $20 = $6
=> $6 = 15% of saving => saving = $40
=> Jay's allowance = $40 + $20 = $60

cheers...

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