A proportion looks like this:
It means that the quantity a,b,c and d are in the same proportion: the ratio between a and b is the same ratio between c and d.
They are particularly useful in situation when you have an example given, and you want to extrapolate the relationship for another couple.
For example, you can think of the following problem: "Five apples cost 2 dollars. How much will 8 apples cost?"
You can build the proportion
And then solve it for x:
Answer:
7. 5 pizza
8. B
9. 11 inches
10. -12
11.
12. 4
Step-by-step explanation:
7. 3 + 2
make them mixed fractions: +
get a common denominator by multiplying by 4:
+
add the numerators:
simplify the fraction by dividing 45 by 8: 5
8. 3 x 6 = 18
5 x 6 = 30
7 x 6 = 42
9 x 6 = 54
therefore, y = 6x
9. 5:7 is similar to 8:L
divide 8 by 5: 1
multiply 7 by 1 : 11
L = 11 inches
10. 5 - 2x = 29
subtract 5 from each side: -2x = 24
divide each side by -2: x = -12
11. fruit = 15%
15% = 15/100
simplify by dividing by 5:
12. the y-intercept is where the line crosses the y-axis (the vertical one). the line crosses the y-axis at 4.