Q&A - PSLE Math

[JadeDry]

Hello,


I would appreciate input on the following question-

Make b the subject of the formula

((a squared) / (x squared)) + ((b squared) / (y squared)) = 1

My answer is ( b= square root of (y squared( x squared - a squared)) / (x squared)

Is this correct?

Thanks in advance.

[MathIzzzFun]

JadeDry:

Hello,


I would appreciate input on the following question-

Make b the subject of the formula

((a squared) / (x squared)) + ((b squared) / (y squared)) = 1

My answer is ( b= square root of (y squared( x squared - a squared)) / (x squared)

Is this correct?

Thanks in advance.

Hi

http://i39.tinypic.com/1zqsw7t.jpg\">

btw, is this p6/psle maths ? I would suggest that you post this at the secondary maths thread in order not to confuse P6 parents/P6 students who are reading this thread.

cheers.

[oliveminx]

5) At first, Ravi had $200 more than Vincent. He gave 40% of his money to Vincent. Vincent then gave 25% of his money to Ravi. In the end, Vincent had $68 more than Ravi. How much did Vincent give Ravi?


R[100%][200]
V[100%]

R[60%][ 120 ]
V[140%][80]

R[95%][140]–68-
V[ 105% ][60]

10%=208-60=148
35%=518
518+20=538

[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.