Q&A - PSLE Math

[Shimmer]

1)In a online quiz,30 points are awarded for every correct answer. 10 points are deduct for every wrong answer. Alex has 2570 points for answering 103 questions.

How many questions did Alex answer again?

2)A stall sold 3 kinds of juice. Coconut are at $3,Sugar Cane cost$2 and Guava cost $1.The number of juice sold for 3 data is in a ratio of 3:6:11,find the average cost each bottle sold during 3 days .

3)Owen made 100 sandwich for $100.Chicken are sold for $5 each, fish are sold for $2 and plain are sold for $0.10.How many sandwich did she for each flavor ?

4) A fruit seller had two box of fruits. Each box had mangoes and pears.
The ratio of mangoes tO pear in bOx was 5:4. In box B the number of pear was 2/5 of mangoes. The seller transferred half of the pears in A to B.In the end the fruits in A become 105 and the ratio of mangoes to Pear is 7:4.
A) How many pears were transferred frome A to B?
B)How many fruits are in B in the end?

[Zhu99]

Shimmer:

1)Ben was given some money. He realised that If he had spent 0.8 cents for each meal, he wOuld have 8 meals fewer if he had spent 0.6 cents per meal.

Ben spent 0.6 cent on 8 meals and spent 0.8 cents on the remaining meals. How many meal did the money last him?

0.6 x 8 = 4.8 --- Amt saved from the 8 meals at 0.6 cents

0.8 - 0.6 = 0.2 --- Additional cost of each meal at 0.8 cents

4.8/0.2 = 24 --- No. of meals at 0.8 cents

24 x 0.8 = 19.2 --- Total amt of money

0.6 x 8 = 4.8 --- Amt spent on 8 meals at 0.6 cents

19.2 - 4.8 = 14.4 --- Remaining amt spent at 0.8 cents

14.4/0.8 = 18 --- No. of meals at 0.8 cents

18 + 8 = 26

The money lasted for 26 meals.

Shimmer:

2)Machine P and Q are use to print a book in 5h. When printing a book , P broke down. As a result, it took 7 h to finsh a book. It took Q 8h 20 min to finish printing a book alone.
A. How long P was used before it broke down?
B. How does p take to print a book?

P+Q: 5 h ---> 1 Book
P+Q: 1 h ---> 1/5 Book

Q: 8 1/3 h ---> 1 Book
Q: 1 h ---> 1 x 3/25 = 3/25 Book
Q: 7 h ---> 3/25 x 7 = 21/25 Book

1 - 21/25 = 4/25 Book -- Done by P

P: 1 h ---> 1/5 - 3/25 = 2/25 Book
P: 4/25 Book ---> 1 x 25/2 x 4/25 = 2 h

a) P was used for 2 h.

P: 1 Book --> 1 x 25/2 x 1 = 12 1/2 h

b) It took P 12 1/2 h to print a book (alone).

[zanen]

hello. can someone help me? please help me...both my tuition teachers refuse to...:( some boys sat in a circle. 41 fruit tarts were passed around the boys. alan happened to receive the first and last fruit tarts he received a total of 6fruit tarts. how many boys are there?

[Zhu99]

zanen:

hello. can someone help me? please help me...both my tuition teachers refuse to...:( some boys sat in a circle. 41 fruit tarts were passed around the boys. alan happened to receive the first and last fruit tarts he received a total of 6fruit tarts. how many boys are there?

41 - 1 = 40 --- Disregard the 1st fruit tart Alan received

6 - 1 = 5 --- Number of rounds

40/5 = 8 --- No. of boys

There are 8 boys.

Alan --- 1st, 9th, 17th, 25th, 33th, 41st

[Clairifina]

Hi, can somebody please help with this question? It will be much appreciated. Thank you in advance!


Store X sells an ipad at $660 which is 20% more than the price at store Y. During The Great Singapore Sale, both stores offered the same percentage discount for the iPad. Mr Lee bought the iPad from store Y and paid $104.50 less than the discounted price at store X. What is the percentage discount?

[kiasuaunt]

:thankyou: Zhu99 for your clear explanation. I understand now.

[zanen]

Zhu99:

zanen:

hello. can someone help me? please help me...both my tuition teachers refuse to...:( some boys sat in a circle. 41 fruit tarts were passed around the boys. alan happened to receive the first and last fruit tarts he received a total of 6fruit tarts. how many boys are there?

41 - 1 = 40 --- Disregard the 1st fruit tart Alan received

6 - 1 = 5 --- Number of rounds

40/5 = 8 --- No. of boys

There are 8 boys.

Alan --- 1st, 9th, 17th, 25th, 33th, 41st

may you explain to me why must disregard the lst one by alan?

[nounou]

Hi Tianzhu, can you please explain the following?


146 – (1+2) ------143 (71 and 72)
Why – (1+2)? Why -? Why 1? Why +2? :gloomy:
:udaman: :thankyou:

tianzhu:

Treelodge:

Q15 part 2. Uncle Tianzhu, you have lao hua ah?

Hi

I've to admit I cannot resist the onslaught of old age.

Try to enlarge your images in the future so that we can see better.

The numbers on one side of a sheet adds up to 146.

bi ------21,22 and 51,52

146 – (1+2) ------143 (71 and 72)

Hence number of photos -------- 72

Best wishes

[MathIzzzFun]

Clairifina:

Hi, can somebody please help with this question? It will be much appreciated. Thank you in advance!


Store X sells an ipad at $660 which is 20% more than the price at store Y. During The Great Singapore Sale, both stores offered the same percentage discount for the iPad. Mr Lee bought the iPad from store Y and paid $104.50 less than the discounted price at store X. What is the percentage discount?

20/120 x $660 = $110 --> Price of the ipad at Store X is $110 more than that at Store Y.

$104.50/$110 x100% =95%
Discount -->100%-95% = 5%

cheers.

[MathIzzzFun]

Treelodge:

Q15 part 1 http://i48.tinypic.com/1gmxiw.jpg\">

tianzhu:

[quote=\"Treelodge\"]http://i48.tinypic.com/11t9wz6.jpg\"> Very pai seh! :imsorry: Another Q from Nanyang Prelim 2012. Q15. :gloomy: Someone please tell (lie to) me actual PSLE Maths is not that difficult.
How to do bi and bii? Answers given bi=21, 22, 51,52 bii=72
:thankyou: :thankyou: :thankyou: [img]

Hi

Could we have a clearer image, please?

Best wishes

[/quote]suppose we have a 60 page newspapers --> page number of 1st page + page number on last page = 1 + 60 = 61 --> total number of pages = 61-1=60

applying the same concept here..we have
on the sheet given, the photo numbers are 21, 22 & 51, 52
21+52= 73
22+51= 73
Total number of photos = 73-1 = 72

cheers