kmeds16
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?
Delete
Share
This Question is Closed
goformit100
Best Response
You've already chosen the best response.
0
ok
kmeds16
Best Response
You've already chosen the best response.
1
@Decart show me the solution please :)
kmeds16
Best Response
You've already chosen the best response.
1
Ah ok I got it by fingers. But is there any mathematecal equation to solve this kind of problem? Its like a riddle.
Decart
Best Response
You've already chosen the best response.
0
boys = x girls = y
campbell_st
Best Response
You've already chosen the best response.
0
there are 7 children, 4 boys and 3 girls...
kmeds16
Best Response
You've already chosen the best response.
1
@campbell_st can you show me your solution?
campbell_st
Best Response
You've already chosen the best response.
0
plenty of options...
cwrw238
Best Response
You've already chosen the best response.
1
i find this quite tricky..
Decart
Best Response
You've already chosen the best response.
0
two equations two unknowns
campbell_st
Best Response
You've already chosen the best response.
0
if you rewrite Decarts equations you have
y = -1 and 0.5y - x = 1
kmeds16
Best Response
You've already chosen the best response.
1
oh wait. im still trying to figure it out. its tricky :/
campbell_st
Best Response
You've already chosen the best response.
0
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
cwrw238
Best Response
You've already chosen the best response.
1
- thats probably the best way
i've got a headache trying to create the equations
Decart
Best Response
You've already chosen the best response.
0
but we can get them
cwrw238
Best Response
You've already chosen the best response.
1
maybe i need another coffee - lol
kmeds16
Best Response
You've already chosen the best response.
1
@cwrw238 haha, my brother too. until he left me here alone :/
Decart
Best Response
You've already chosen the best response.
0
brother = x+y sister=x+.5y
Decart
Best Response
You've already chosen the best response.
0
.5y when we took one away
Decart
Best Response
You've already chosen the best response.
0
sister = 2x+y
Decart
Best Response
You've already chosen the best response.
0
brother is actually x+1
Decart
Best Response
You've already chosen the best response.
0
x+1brother has x-1+y x-1 being himself
cwrw238
Best Response
You've already chosen the best response.
1
1 + 2x = x + y
where x = girls, y = boys is one equation
Decart
Best Response
You've already chosen the best response.
0
x+1+y=y-1+2x
cwrw238
Best Response
You've already chosen the best response.
1
that gives x + 1 = 1 + 2x
giving x=0
kmeds16
Best Response
You've already chosen the best response.
1
i formulated an equation XD
x - 1 = y
y - 1 = x/2
cwrw238
Best Response
You've already chosen the best response.
1
x - 1 = 0.5y is another
so u have
1 + 2x = x + y
x -1 = 0.5y
is that right??
kmeds16
Best Response
You've already chosen the best response.
1
@cwrw238 i'll try to solve yours & you try mine :)
cwrw238
Best Response
You've already chosen the best response.
1
yes that gives x = 3 y=4
cwrw238
Best Response
You've already chosen the best response.
1
oh ok
Decart
Best Response
You've already chosen the best response.
0
awesome
cwrw238
Best Response
You've already chosen the best response.
1
x - 1 = y
y - 1 = 0.5x
add
x - 2 = 0.5x
x = 4
y = 4-1 = 3
cwrw238
Best Response
You've already chosen the best response.
1
in your equation x = boys , y = girls right?
yours come out right too
kmeds16
Best Response
You've already chosen the best response.
1
ya and yours is x = girls and y = boys,right?
cwrw238
Best Response
You've already chosen the best response.
1
yea
well done
kmeds16
Best Response
You've already chosen the best response.
1
thank you @cwrw238 :)