Here the two samples should be comparable .
The total number of cows in the farm = 200
the total number of cows giving milk = 150
the total number of cows in corral = 20
Suppose total number of cows giving milk in corral = x
The ratio of the total number of cows present to the total number of cows giving milk should be same in farm and corral
so : 200 = 20
------- -------
150 x
now we do cross multiplication :
200 x = 150* 20
200x = 3000
x= 3000/200
x= 15
SO we expect 15 cows in corral should be giving milk .
Answer : 15
It's a lot like solving equations.
3b-7 < 32
Add 7 to each side.
3b < 39
Divide by 3 on each side.
b < 13
Hope this helps :)
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1 cm = 10mm
5 mm : 10mm : :1 : 2
hoped i helped. ^-^
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