Q&A - PSLE Math

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

Post by Steadyberry » Mon Jun 13, 2016 12:49 pm

Pls help. Thanks very much.

1) Donna bought some bags at $10 each and sold them at $19 each. For customers who bought 2 bags, she gave them 1 bag free. If she earned $925 and gave away 11 free bags, how many customers bought only one bag?


2) At 11.45 am, a car left town A at a constant speed of 60 km/h. At 12.30 pm, a motorcycle left the same place and travelled at a constant speed. After travelling 195 km, the motorcycle caught up with the car. The motorcycle travelled at the same speed then stopped for a 30-minute break at 4.45 pm before continuing at the same speed. How far apart would the two vehicles be at 6.30 pm?

BigDevil
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Re: Q&A - PSLE Math

Post by BigDevil » Mon Jun 13, 2016 3:40 pm

Steadyberry wrote: 1) Donna bought some bags at $10 each and sold them at $19 each. For customers who bought 2 bags, she gave them 1 bag free. If she earned $925 and gave away 11 free bags, how many customers bought only one bag?
The 11 bags given for free cost $110.
If Donna hadn't given away any free bags, she would have earned 925 + 110 = $1035.

1035 / 9 = 115 bags sold.
11 free bags means 22 bags were sold as sets of 2.

Number of customers who bought one bag -> 115 - 22 = 93

alfretztay
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Re: Q&A - PSLE Math

Post by alfretztay » Mon Jun 13, 2016 4:00 pm

Steadyberry wrote:Pls help. Thanks very much.

1) Donna bought some bags at $10 each and sold them at $19 each. For customers who bought 2 bags, she gave them 1 bag free. If she earned $925 and gave away 11 free bags, how many customers bought only one bag?


2) At 11.45 am, a car left town A at a constant speed of 60 km/h. At 12.30 pm, a motorcycle left the same place and travelled at a constant speed. After travelling 195 km, the motorcycle caught up with the car. The motorcycle travelled at the same speed then stopped for a 30-minute break at 4.45 pm before continuing at the same speed. How far apart would the two vehicles be at 6.30 pm?
I would solve the above 2 questions as follows :

1. Donna bought some bags at $10 each and sold them at $19 each. For customers who bought 2 bags, she gave them 1 bag free. If she earned $925 and gave away 11 free bags, how many customers bought only one bag?


11 free bags + 22 paid bags ------- received 418; cost 330; earned 88

925 - 88 = 837

19 - 10 = 9

837/9 = 93 (bags sold singly)


Ans : 93 customers.



2. At 11.45 am, a car left town A at a constant speed of 60 km/h. At 12.30 pm, a motorcycle left the same place and travelled at a constant speed. After travelling 195 km, the motorcycle caught up with the car. The motorcycle travelled at the same speed then stopped for a 30-minute break at 4.45 pm before continuing at the same speed. How far apart would the two vehicles be at 6.30 pm?



11.45am to 12.30pm ------- 45min or 0.75h

60 x 0.75 = 45 (km; car ahead of motorcycle at 12.30pm)

195 - 45 = 150 (km)

150/60 = 2.5 (h)

195/2.5 = 78(km/h; speed of motorcycle)

11.45am to 6.30pm ------- 6h 45min or 6.75h

6.75 x 60 = 405 (km, distance travelled by car)

12.30pm to 6.30pm ------- 6h

6h less 30min = 5.5h

5.5 x 78 = 429

429 - 405 = 24



Alternatively,

11.45am to 12.30pm ------- 45min or 0.75h

60 x 0.75 = 45 (km; car ahead of motorcycle at 12.30pm)

195 - 45 = 150 (km)

150/60 = 2.5 (h)

195/2.5 = 78(km/h; speed of motorcycle)

2.5h after 12.30pm ------- 3pm (motorcycle caught up with the car)

3pm to 6.30pm ------- 3.5h

3.5 x 60 = 210

3.5h less 30min ------- 3h

78 x 3 = 234

234 - 210 = 24



Ans : 24km.

Fly2high
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Re: Q&A - PSLE Math

Post by Fly2high » Mon Jun 13, 2016 4:18 pm

Hi ,

Pls help on the below questions . Thank u in advance !

1. Mr.Lee bought 500 notepads. He sold 50% of them at a selling price of $1.50 each and 30% of the remainder at a discount of
10% each . He then sold the rest of the notepads at cost price. After deducing the cost of the notepads,Mr. Lee collected a total
Of $86.25 from the sale of all the notepads. What was the cost price
Of each notepad ?

2. A rectangular piece of paper with breadth 6cm was rolled up, without
Overlapping ,to form a hollow cylindrical tube . Find the perimeter
Of the rectangular piece of paper if the circumference of the tube is 22cm .


Thanks !

Sruthi
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Re: Q&A - PSLE Math

Post by Sruthi » Mon Jun 13, 2016 11:52 pm

Please help with the question Image


Ice watch
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Re: Q&A - PSLE Math

Post by Ice watch » Tue Jun 14, 2016 1:01 am

Sruthi wrote:Please help with the question Image

Image

BigDevil
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Re: Q&A - PSLE Math

Post by BigDevil » Tue Jun 14, 2016 9:58 am

Fly2high wrote: 1. Mr.Lee bought 500 notepads. He sold 50% of them at a selling price of $1.50 each and 30% of the remainder at a discount of
10% each . He then sold the rest of the notepads at cost price. After deducing the cost of the notepads,Mr. Lee collected a total
Of $86.25 from the sale of all the notepads. What was the cost price
Of each notepad ?
Number of notepads sold at $1.50 -> 50% x 500 = 250
Number of notepads sold at $1.35 (10% discount) -> 30% x 250 = 75
Remaining 175 notepads were sold at cost, so they don't contribute to
final profit of $86.25.

250 x $1.50 = $375
75 x $1.35 = $101.25
Total -> 375 + 101.25 = 476.25

476.25 - 86.25 = 390 (Cost of 250 + 75 = 325 notepads)
Cost of each notepad -> 390 / 325 = $1.20

BigDevil
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Re: Q&A - PSLE Math

Post by BigDevil » Tue Jun 14, 2016 10:06 am

Fly2high wrote: 2. A rectangular piece of paper with breadth 6cm was rolled up, without
Overlapping ,to form a hollow cylindrical tube . Find the perimeter
Of the rectangular piece of paper if the circumference of the tube is 22cm .
Unroll the tube and you will get a piece of paper of 22cm x 6cm.

Fly2high
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Re: Q&A - PSLE Math

Post by Fly2high » Tue Jun 14, 2016 10:19 am

Thanks very much BigDevil !!

BigDevil
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Re: Q&A - PSLE Math

Post by BigDevil » Tue Jun 14, 2016 12:17 pm

You are welcome :)

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