Q&A - PSLE Math

[just888]

JE382:

One more question :

In the figure that is not drawn to scale, ABCF is a rectangle. Find the area of the shaded parts.
http://i44.tinypic.com/10s9jfb.png\">

http://i41.tinypic.com/2jciloo.png\">

Name the line intersection point of AD and BE line G
Area of shaded area x
= Area of triangle BDG
= Area of triangle ADB - Area of the triangle AGB
= (1/2 x 12 x 9) - (1/2 x 12 x 7)
= 54 - 42
= 12

Area of the shaded area y
= Area of triangle AEG
= Area of triangle AEB - Area of triangle AGB
= (1/2 x 12 x 9) - (1/2 x 12 x 7)
= 54 - 42
= 12

Area of the shaded parts
= Area of the x + Area of y
= 12 + 12
= 24

[oliveminx]

maychang:

Hi Oliveminx,
Thanks for your reply.
JE382 is my DD, she is going to sit for psle next year.
She draws the diagram herself as we do not have a scanner at home.
Will get her to repost the diagram in bigger size.

I think BD and AE are supposed to be straight lines. If so, the two solutions posted are correct.

[JE382]

tianzhu:

JE382:

One more question :

In the figure that is not drawn to scale, ABCF is a rectangle. Find the area of the shaded parts.
http://i44.tinypic.com/10s9jfb.png\">

Hi

It’s helpful to have a bigger image.Is line BE a straight line?

In answering this question, I assume that line BE is a straight line
The two shaded areas are of equal sizes.

Area of triangle ABD ----- ½ * 12 * 9 ------ 54
Area of triangle (height 7 cm) ----- ½ * 12 * 7 ------ 42

Difference of 1 shaded part ------ 54 – 42 -----12
Area of 2 shaded parts ------ 12*2 ----- 24

Best wishes

Yes, line BE is a straight line. Thanks for your answer too!
:thankyou:

[JE382]

Thanks to everyone who have answered my questions!!

[tianzhu]

JE382:

Yes, line BE is a straight line. Thanks for your answer too!
:thankyou:

Hi

You're welcome.

Best wishes

[elkniwt]

Hi,


Like to ask a general question on \"part thereof\" :

For qns like, (make-up qn, so forgive me for any phrasing error.. )
Cost of postage is $10 for the first 100g and $2 for the subsequent additional 10g. What is the cost of postage for a 123g parcel?

Please advise what is the difference in answer (if any) with or without the phrase \"part thereof\".

Thank you very much.

[tianzhu]

Hi elkniwt


Good Morning.

I suggest you take a look at the actual exam questions on this topic.When students are expected to use \"part thereof \",usually, it's expressed in the question.Otherwise, the cost for subsequent units is given.

If I remember correctly, additional charges are usually in;

a) Part thereof ----- common question hinges around parking charges at the car park.

Every subsequent half hour or part thereof ----- $1.50\t

Part thereof means there would be a full charge of $1.50 for any time from 1 minute to 29 minutes

b) Additional charges can also be expressed in cost per unit or per set for subsequent units.

1) cost per page ----- Subsequent pages --- 3 cents per page

2) cost per additional toy ----- For each subsequent toy --- $0.50 per toy

3) cost per set or group ---- Subsequent 5 litres --- $3

Best wishes.

[elkniwt]

Dear tianzhu,


Firstly, thank you very much for your help time and again. Really appreciate.

My dd encountered this qn from her school worksheet. It goes :
Q1) A taxi driver charges $2.60 for the first km and 10c per additional 195m. How much must a passenger pay for a journey of 12km?
She got the answer $8.30 [$2.60 for first km + 57 x 10c for the remaining distance]. She was marked wrong. Her teacher explained that since there is no "part thereof" in the question, the extra 80m which is less than 195m should be excluded. Teacher’s answer is $8.20 [$2.60 + 56 x 10c]

Then she encountered another question from Rosyth paper.
Q2) The table below shows the airmail rates to America.
First 20g -> $1.10
Additional 10g -> $0.35
Find the cost of airmail which weighs 29g.

Her answer is $1.10 (since there is no part thereof in the question).
This time, the answer given is $1.45 [$1.10 + 1 x $0.35] .

Hence, both of us are baffled. ???

[tianzhu]

Hi elkniwt


You’re welcome.

Please refer to MathIzzzFun’s post below.

Best wishes

[MathIzzzFun]

elkniwt:

Dear tianzhu,


Firstly, thank you very much for your help time and again. Really appreciate.

My dd encountered this qn from her school worksheet. It goes :
Q1) A taxi driver charges $2.60 for the first km and 10c per additional 195m. How much must a passenger pay for a journey of 12km?
She got the answer $8.30 [$2.60 for first km + 57 x 10c for the remaining distance]. She was marked wrong. Her teacher explained that since there is no \"part thereof\" in the question, the extra 80m which is less than 195m should be excluded. Teacher's answer is $8.20 [$2.60 + 56 x 10c]

Then she encountered another question from Rosyth paper.
Q2) The table below shows the airmail rates to America.
First 20g -> $1.10
Additional 10g -> $0.35
Find the cost of airmail which weighs 29g.

Her answer is $1.10 (since there is no part thereof in the question).
This time, the answer given is $1.45 [$1.10 + 1 x $0.35] .

Hence, both of us are baffled. ???

Hi

the teachers are right.

1) for taxi meter, fares are paid according to distance travelled ie if the distance travelled is 1km 190m then the fare is just starting fare ie $2.60 in this case. The fare will increase to $2.70 at 1195m.

2) for air mail, rates are charged according to how heavy each package weighs.. so additional 10g would actually means \"up to additional 10g\".

cheers.