Q&A - PSLE Math

[fathima]

How to do overlapping sums Primary 6 child for PSLE ?

[fathima]

6 / 2 = 3

1/2 X pi X 3 X 3 = 4.5 pi
8 / 2 = 4
1/2 X pi X 4 X 4 = 8 pi
8 pi + 4.5 pi = 12.5 p


ANSWER: 12.5 pi cm2

[lesskiasu]

tianzhu:

lesskiasu:

Hi, can anyone help on to this question? The question is Catholic High Prelim 2011. http://i45.tinypic.com/2ryfq6o.jpg\">

Hi

Students are requested to leave their answers in terms of pi.

Apply the formula for calculating the area of a semi circle, and you should get an answer of 12.5pi.

Best wishes

Thanks Tianzhu for the answer. My dd couldn't figure out the working thus no answer for this.
Will get her do it next time to post the question together with the answer.
:thankyou:

[peggy]

Kindly assist.



A number of passengers boarded an empty MRT train at pasir ris station.

At Tampines station, 2/5 of them alighted and 80 boarded the train.
At Simei station, 223 alighted and 38 boarded the train.
The train now has 3/8 of the number of passengers when it left Tampines station.

A. How many passengers were on the train when it left Simei station?
B. How many passengers were on the train when it left Pasir Ris station?

Thank you.

[zanen]

hello can help me with Peichun prelim 2012 qn 15 on circles? my laptop cannot upload photo. thanks

[MathIzzzFun]

zanen:

hello can help me with Peichun prelim 2012 qn 15 on circles? my laptop cannot upload photo. thanks

http://tinyurl.com/mathizzzfun-PeiChun-2012Prelim


cheers.

[zanen]

thanks MathIzzzFun can help me wif this too? Henry bought a box of pen and another box of pencils to sell them in the night market.The cost of a pen and a pencil was $12 and $8 respectively.In week 1,the same number of pen and pencil were sold and the total amount collectd by Henry was $1980.In week 2,67 pens and pencils were sold altogether.Henry collected $720 more from the sale of pens than pencils for the 2 weeks.How many pens were sold altogether in the 2 weeks?

[MathIzzzFun]

zanen:

thanks MathIzzzFun can help me wif this too? Henry bought a box of pen and another box of pencils to sell them in the night market.The cost of a pen and a pencil was $12 and $8 respectively.In week 1,the same number of pen and pencil were sold and the total amount collectd by Henry was $1980.In week 2,67 pens and pencils were sold altogether.Henry collected $720 more from the sale of pens than pencils for the 2 weeks.How many pens were sold altogether in the 2 weeks?

1 set of 1 pen + 1 pencil --> $20
Number of sets sold in week 1 --> $1980/$20 = 99

$12-$8 = $4 --> 1 pen cost $4 more than 1 pencil
99 x $4 = $396 --> Henry collected $396 more from sale of pens than pencils in week 1

$720-$396 = $324 --> Henry collected $324 more from sale of pens than pencils in week 2.
Number of pencils sold in week 2 --> (67x$12-$324)/($12+$8) = 24
Number of pens sold in week2 = 43
Total number of pens sold in 2 weeks = 43 + 99 = 142

cheers.

[jewelbox]

Appreciate any help on this qn (RGS SA1 2012) : http://i49.tinypic.com/i1invc.jpg\">

[tianzhu]

peggy:

Kindly assist.



A number of passengers boarded an empty MRT train at pasir ris station.

At Tampines station, 2/5 of them alighted and 80 boarded the train.
At Simei station, 223 alighted and 38 boarded the train.
The train now has 3/8 of the number of passengers when it left Tampines station.

A. How many passengers were on the train when it left Simei station?
B. How many passengers were on the train when it left Pasir Ris station?

Thank you.

Hi

Good Morning.

You may use MD or work with units.

It helps to have a simple diagram to show the flow of events.

The number of passengers leaving one station is the same as the number of passengers arriving at the next station.

Pasir Ris -------- 40 units

Tampines

At first -------- 40 units

2/5 of them alighted and 80 boarded the train.

Alighted ------- 16 units

Left ------- 24 units + 80

Simei

At first ------- 24 units + 80

223 alighted and 38 boarded the train.

Left -------- 24 units + 80 - 223 + 38 -------- 24 units – 105

The train now has 3/8 of the number of passengers when it left Tampines station.

24 units – 105 -------- 9 units + 30 (3/8 of 24 units + 80)

1 unit ------ 9

a)Number of passengers leaving Simei station ------- 9*9 + 30 -------- 111

b)Number of passengers leaving Pasir Ris station ------- 40*9 ------- 360.

Best wishes