Question

In a family, each boy has as many sisters as brothers, but each sister has only half as many sisters as brothers. How many children are there in the family?

Answer 1

ok

Answer 2

@Decart show me the solution please :)

Answer 3

Ah ok I got it by fingers. But is there any mathematecal equation to solve this kind of problem? Its like a riddle.

Answer 4

boys = x girls = y

Answer 5

there are 7 children, 4 boys and 3 girls...

Answer 6

@campbell_st can you show me your solution?

Answer 7

plenty of options...

Answer 8

i find this quite tricky..

Answer 9

two equations two unknowns

Answer 10

if you rewrite Decarts equations you have

y = -1 and 0.5y - x = 1

Answer 11

oh wait. im still trying to figure it out. its tricky :/

Answer 12

for me it was trial and error knowing that there needed to be an odd number of children

I knew 3 doesn't work, 5 works for the boy having equal sisters and brothers but doesn't work for the girl,

so try 7

works

Answer 13

- thats probably the best way
i've got a headache trying to create the equations

Answer 14

but we can get them

Answer 15

maybe i need another coffee - lol

Answer 16

@cwrw238 haha, my brother too. until he left me here alone :/

Answer 17

brother = x+y sister=x+.5y

Answer 18

.5y when we took one away

Answer 19

sister = 2x+y

Answer 20

brother is actually x+1

Answer 21

x+1brother has x-1+y x-1 being himself

Answer 22

1 + 2x = x + y
where x = girls, y = boys is one equation

Answer 23

x+1+y=y-1+2x

Answer 24

that gives x + 1 = 1 + 2x
giving x=0

Answer 25

i formulated an equation XD

x - 1 = y
y - 1 = x/2

Answer 26

x - 1 = 0.5y is another

so u have

1 + 2x = x + y
x -1 = 0.5y

is that right??

Answer 27

@cwrw238 i'll try to solve yours & you try mine :)

Answer 28

yes that gives x = 3 y=4

Answer 29

oh ok

Answer 30

awesome

Answer 31

x - 1 = y
y - 1 = 0.5x

add
x - 2 = 0.5x
x = 4

y = 4-1 = 3

Answer 32

in your equation x = boys , y = girls right?

yours come out right too

Answer 33

ya and yours is x = girls and y = boys,right?

Answer 34

yea

well done

Answer 35

thank you @cwrw238 :)