## Friday, November 13, 2015

### Counting (number of pairs of perpendicular and parallel lines) ( combinatorics)

For each of the figures below, find the number of:
(a) parallel lines (including line segments)
(b) perpendicular lines (including line segments)
> For each of the figures below, find the number of
> (a) parallel lines (including line segments)
> (b) perpendicular lines (including line segments)
>>

## Wednesday, November 4, 2015

### P5 Ratio, external transfer (Fr: CCL)

Q1.
The ratio of the number of boys to the number of girls in a school is 7 : 6.
After twice as many boys as girls left the school, the ratio became 4 : 5 .
There were 575 girls in the school in the end.
(a)  How many girls were in the school at first?
(b)  How many more boys than girls left the school?

Q2.
The ratio of the number of boys to the number of girls in a school is 7 : 6.
After some girls joined the school and twice as many boys left the school, the ratio became 4 : 7 .
There were 931 girls in the school in the end.
(a)  How many girls were in the school at first?
(b)  How many boys left the school?

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The above were modified question from...