Q&A - P5 Math

[snowball]

PapayaDad:

The first even number is 22 and the last is 80 and they total 102.

The second and second last 24 and 78 and they total 102 also.
And the list goes on and we can make multiple pairs totalling 102.
There are 30 even number, so we can make 15 pairs (last pair is 50 and 52).
15 x 102 = 1530

How to calculate there r 30 even no.?
Any shortcut formula?

[PapayaDad]

From 21 to 80 there are 60 numbers.

Half is odd, half is even.

[smartmummy]

pls guide me.

how to do the following type qns
rearrange the following fractions in ascending order
3/4,7/8,5/6,11/12,8/9
for small numbers we can find the least common mutiple, then can rearrange.For big numbers also have to do like that or any short cut available?.
thanks in advance.

[PapayaDad]

How far are they from 1? the further they are from 1 the smaller they are, the nearer to 1 they are bigger. So,


3/4 is 1/4 a way from 1
7/8 is 1/8 away from 1
5/6 is 1/6 away from 1
11/12 is 1/12 away from 1
8/9 is 1/9 from 1

so,
11/12 is biggest
3/4 is smallest

can work out the rest already

[smartmummy]

thanks papayadad

[tianzhu]

newuser:

I am lost in explaining to this DS.
Anyone can help to draw MD for us to visualize?

Hi

Hope this helps.

Best wishes

http://farm9.staticflickr.com/8521/8597362780_3351ff8915_z.jpg\">

[Jamesbond]

quekcc:

Jamesbond:

http://i50.tinypic.com/fcv5hc.jpg\">

Help needed.

Find area of triangle ACD, and take away area of triangles AEO, EDF and FOC.

Note that AE=4, ED=16, DF=3, FC=9.

Area of ACD = 120
Area of AEO = 12 (height is 6)
Area of EDF = 24
Area of FOC = 45 (height is 10)

Answer = 39

:thankyou: queckcc

[Jamesbond]

http://i46.tinypic.com/161ant.jpg\">

Pl help....

[carol73]

pls help to provide ans to the below, I want to confirm if my solution is correct


There were 147 glasses for sale. 10/21 of them were blue and the rest were yellow. When some blue glasses were sold, the number of blue glassess left was 4/15 of the total number of glasses left, how many blue glasses were sold.


there were 889 pupils in a school. 1/3 o fthe girls and 1/2 of the boys were in the upper primary classess. there were equal number of boys and girls in the lower primary classes. find the number of girls and the number of boys in the school

[ChewingPencilLine]

carol73:

pls help to provide ans to the below, I want to confirm if my solution is correct


There were 147 glasses for sale. 10/21 of them were blue and the rest were yellow. When some blue glasses were sold, the number of blue glassess left was 4/15 of the total number of glasses left, how many blue glasses were sold.


there were 889 pupils in a school. 1/3 of the girls and 1/2 of the boys were in the upper primary classes. there were equal number of boys and girls in the lower primary classes. find the number of girls and the number of boys in the school

Q1: 42
Q2: 381 girls, 508 boys