chrisu:

Thank you, didn't realise it's just so straight forward. Makes my day.

PiggyLalala:

[quote=\"chrisu\"]Hi need help for this question;

The figure below, not drawn to scale, shows 2 semi-circles and a right-angled triangle overlapping one another. The diameter of the smaller semi-circle is half of the bigger semi-circle. Find the area of the shaded part given that the diameter of the bigger semi-circle is 40cm.
Give your answer correct to 2 decimal places.

http://img.photobucket.com/albums/v160/guppiesonli/Misc/Q18.jpg\">

area of shaded area = area of big semicircle + area of small semicircle - area of triangle
= 0.5 X3.142 X 20 X 20 + 0.5 X3.142 X 10 X 10 - 1/2 X 20 X 40 ( use the calculator pie)
=385.40 cm square

[/quote]Hi, can anyone enlighten me on why areas of semicircles minus triangle gives the shaded area??
TIA

fifiyeo:

Hi! Does anyone own a Philips Airfryer or a Tefal Actifry?

Hi, Fifi, thanks for sharing about the roomba and scooba.
Now looking at airfryer. Heard that Tefal Actifry is good.

Anyone has anything to share about it?

:thankyou:

atrecord:

you might be able to google something of interest too. When I was assessing the avc's, i remember seeing a youtube video of someone comparing the iclebo, irobot and the samsung navibot. in the video, someone has a odd-shaped room, with a camera installed at a high location, then pour i think some coloured powder on the whole floor, then took turns to let the 3 avc's clean up the place. when they go past, the powder will be sucked up by the avc's so it's quite obvious which one is better or worse...

Hi, so which one performed best?
thanks

Alvin 8228:

hazelwong:

Hi, can anyone help with this question?

In an auditorium, the ratio of boys to girls was 3:5.
1/4 of the boys and 68 girls left the auditorium.
In the end, there were 24 more girls than boys left in the auditorium. How many boys were there at first?

Thanks v much

At first
3:5 = 12:20, boys : girls , 12u : 20u

1/4 boys left = 3/12 3u left leaving 9u and 68 girls left.


9u : 20u-68 is equal to 24 more boys than girls so

9u = 20u - 68 + 24

11u = 68-24 = 44

U = 44/11 = 44

There were 12u of boys at first = 12 x 4 = 48 boys

Cheers

Hi thanks v much, there is indeed an error in the question- should be 24 more boys rather than girls.
but how did u decide to convert the ratio from 3:5 to 12:20 at first?
:thankyou:

MathIzzzFun:

hazelwong:

Hi, can anyone help with this question?

In an auditorium, the ratio of boys to girls was 3:5.
1/4 of the boys and 68 girls left the auditorium.
In the end, there were 24 more girls than boys left in the auditorium. How many boys were there at first?

Thanks v much

pls check question... should it be \"42\" more girls left ?

cheers.

Hi sorry the question was printed wrongly in the book, it should have been \"24 more boys\" rather than girls
Thanks v much

Hi, can anyone help with this question?

In an auditorium, the ratio of boys to girls was 3:5.
1/4 of the boys and 68 girls left the auditorium.
In the end, there were 24 more girls than boys left in the auditorium. How many boys were there at first?

Thanks v much

MathIzzzFun:

hazelwong:

Hi, can anyone please help with this question?


Observe the following statements:
A+B+C=26
A-B=6
C-B=2
i) Insert a pair of brackets ( ) in the number statement below to illustrate the correct working order to find the value of A
26 – 2 – 6 ÷ 3 + 6
ii) what is the value of A?
Thanks :?:

(26 - 2 - 6) ÷ 3 + 6
...(26-2-6) gives 3B

A = 12

cheers

:thankyou:

Hi, can anyone please help with this question?


Observe the following statements:
A+B+C=26
A-B=6
C-B=2
i) Insert a pair of brackets ( ) in the number statement below to illustrate the correct working order to find the value of A
26 – 2 – 6 ÷ 3 + 6
ii) what is the value of A?
Thanks :?:

MathIzzzFun:

hazelwong:

Hi, can anyone help with this qn?

Mrs tan bought 42 apples. Each apple costs 75cents less than a pear. She spent the same amount of money on 12 pears. How much did Mrs Tan spend on buying the apples?

I managed to solve it only with algebra:
let X be price of pear
42 (X-0.75) = 12X
42X-31.50 = 12X
30X = 31.50
X = 1.05
price of apple 1.05- 0.75 = 0.3
42x0.3 = 12.60
Ans $12.60

Is using algebra ok?
Is there any other way e.g. model or units/parts?
thanks v much

cost of 42 apples = cost of 12 pears
cost of 1 apple = 12/42 cost of 1 pear = 2/7 cost of 1 pear
1 pear --> 7 units
1 apple --> 2 units

1 apple cost 75 cents less than 1 pear,
5 units --> 75 cents
1 unit --> 15 cents

cost of 1 apple --> 30 cents
cost of 42 apples --> 42 x $0.30 = $ 12.60

cheers.

:thankyou:

Hi, can anyone help with this qn?

Mrs tan bought 42 apples. Each apple costs 75cents less than a pear. She spent the same amount of money on 12 pears. How much did Mrs Tan spend on buying the apples?

I managed to solve it only with algebra:
let X be price of pear
42 (X-0.75) = 12X
42X-31.50 = 12X
30X = 31.50
X = 1.05
price of apple 1.05- 0.75 = 0.3
42x0.3 = 12.60
Ans $12.60

Is using algebra ok?
Is there any other way e.g. model or units/parts?
thanks v much