Q&A - PSLE Math

[kiasuaunt]

Spongy:

Hi I need help in 3 questions. Thanks in advance.


1. Hassan had 5 tins of marbles. At first, each of the tins contained the same number of marbles. He took 18 marbles from each tin. After that, the total number of marbles left in the 5 tins was equal to the total number of marbles in 2 of the tins at first. What was the number of marbles in each tin at first?

2. Tickets for a school drama performance were sold to teachers and pupils at different prices. The tickets are sold at $20 each to the teachers and $8 each to the pupils. 1/4 of the tickets sold were bought by teachers. The total amount of money collected from the sale of tickets to pupils was $416 more than the total amount collected from the sale of tickets to teachers. How much money was collected from the sale of tickets altogether?



3. 2 x 2 x 2 x 2 x .......
What is the ones digit in the product of 1000 twos?

Hi Spongy - I can help for Q1 and Q2 - they were PSLE Q.

Q1.Let 1u be the number of marbles left in 1 tin after Hassan took 18 marbles out.

Total number of marbles left in 5 tins = total number of marbles in 2 tins at first

5u = 1u+18+1u+18
5u = 2u + 36
3u = 36
1u = 36/3 = 12 marbles

12+18 = 30 marbles

The number of marbles in each tin at first was 30.

Q2. Fraction of tickets sold to pupils = 1 - 1/4 = 3/4

Diff. in amt collected bet. every 3 pupils and 1 teacher = (3 x $8) - $20
= $4
$416/$4 = 104 sets

Number of pupils = 104 x 3 = 312
Number of teachers = 104
Amt collected = (312 x $8) + (104 x $20)
=$4576

Hope this helps. God Bless.

[MathIzzzFun]

Spongy:

Hi I need help in 3 questions. Thanks in advance.


1. Hassan had 5 tins of marbles. At first, each of the tins contained the same number of marbles. He took 18 marbles from each tin. After that, the total number of marbles left in the 5 tins was equal to the total number of marbles in 2 of the tins at first. What was the number of marbles in each tin at first?

2. Tickets for a school drama performance were sold to teachers and pupils at different prices. The tickets are sold at $20 each to the teachers and $8 each to the pupils. 1/4 of the tickets sold were bought by teachers. The total amount of money collected from the sale of tickets to pupils was $416 more than the total amount collected from the sale of tickets to teachers. How much money was collected from the sale of tickets altogether?

3. 2 x 2 x 2 x 2 x .......
What is the ones digit in the product of 1000 twos?

Hi

for Q3, list out the products in order to see a pattern for the ones digit...

2 -- 2
2x2 -- 4
2x2x2 -- 8
2x2x2x2 -- 16
2x2x2x2 x2 --32
2x2x2x2 x2x2 -- 64
2x2x2x2 x2x2x2 -- 128
2x2x2x2 x2x2x2x2 -- 256

observe that the ones digit will cycle through 2,4,8,6 for every four \"2\"
1000 /4 = 250
so the last digit is 6

(if
1001 \"2\", then 1001/4 = 250 R1 --> last digit 2
1002 \"2\", then 1002/4 = 250 R2 --> last digit 4
1003 \"2\", then 1003/4 = 250 R3 --> last digit


cheers.

[susutoo]

Please help

1) There are more pens in box A than box B. 30% of the pens in box A is 60 more than 40% of the pens in box B. If 5% of the pens in box A is transfered to box B, there will be 300 more pens in box A than box B.
a) How many pens are there in box B?
b) How many percentage less pens are there in box B than box A?

[susutoo]

http://i49.tinypic.com/aoxq3b.jpg\">

Another Q, pls help

[dicoyote]

Packet A, Packet B and Packet C each contained some salt. At first, there were 200g more salt in Packet A than Packet B. Packet C had 3/4 of the amount of salt in Packet A. After 1/8 of the amount of salt in Packet A was transferred to Packet B, there was 82.15g of salt in Packet B. How many percent less salt were there in Packet C than Packet A at first?


Ans is 25%, thanks in advanced

[nounou]

In a cinema, the ratio of the number of girls to the number of boys was 3:2. The ratio of the number of women to the number of boys was 5:4.

The ratio of the number of girls to the number of men was 2:5.
During the movie, 6 women and 27 men left the cinema.
The ratio of the number of women to the number of men then became 1:2.
a) Express the number of women as a fraction of the number of men at first. Leave your answer in its simplest form. --> 1/3
b) How many children were there in the cinema? --> 30 :?:
How to do (b)??? Please help. Many thanks. :thankyou:

[MathIzzzFun]

susutoo:

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Another Q, pls help

Hi

http://postimage.org/image/gyciubnmz/

cheers.

[MathIzzzFun]

dicoyote:

Packet A, Packet B and Packet C each contained some salt. At first, there were 200g more salt in Packet A than Packet B. Packet C had 3/4 of the amount of salt in Packet A. After 1/8 of the amount of salt in Packet A was transferred to Packet B, there was 82.15g of salt in Packet B. How many percent less salt were there in Packet C than Packet A at first?


Ans is 25%, thanks in advanced

Hi

Packet C : Packet A --> 3u : 4u
Difference --> 1u
Percentage less --> 1u/4u x 100% = 25%

cheers.

[MathIzzzFun]

susutoo:

Please help

1) There are more pens in box A than box B. 30% of the pens in box A is 60 more than 40% of the pens in box B. If 5% of the pens in box A is transfered to box B, there will be 300 more pens in box A than box B.
a) How many pens are there in box B?
b) How many percentage less pens are there in box B than box A?

Hi

40% of Box B --> 12 units ---- Box B --> 30 units
30% of A --> 12 units + 60 ----- Box A --> 40 units + 200
5% of Box A --> 2 units + 10
After transfer:

Box B --> 32 units + 10
Box A --> 38 units + 190
So, 38 units + 190 = 32 units + 10 + 300
1 unit --> 20

Box B --> 30 x 20 = 600 pens
Box A --> 40 x 20 + 200 = 1000 pens
(1000-600)/1000 x 100% = 40%
There are 40% less pens in Box B than in Box A.

cheers.

[mumworks]

:thankyou: very much Tianzhu for answering all my questions.