Ratio and Proportion Flashcards
How do you simplify a ratio?
You can divide the numbers on both sides by a common divisor until they can’t be divided anymore.
In a ratio a:b, what is the fraction equivalent to a, and what is the fraction equivalent to b?
a=a/(a+b) and b=b/(a+b).
If you have a ratio, and you know what a is in a:b is, how do you find the value of b?
You divide the number by a and then multiply it by b to get the correct value for b.
If you have a ratio, and you know what a is in a:b is, how do you find the total number?
You divide the number by a and then multiply it by a+b.
If you have a ratio, and you know what |a-b| is in a:b, how do you find a and b?
You divide the number by |a-b| and then multiply it by either a or b.
If you know a ratio of a:b and you know b:c, how can you find the ratio a:c?
You multiply both the ratios until the two values of b are the same. You then just take out the values of a and c and simplify them.
If two variables are in direct proportion and one of them multiplies by a number h, what happens to the other variable?
The other variable is also multiplied by a number of h.
If two variables are in inverse proportion and one of them multiplies by a number h, what happens to the other variable?
The other variable is multiplied by a number of 1/h.
How do you know if two variables are in direct proportion?
One variable will always divide by the other to get the same value.
How do you know if two variables are in inverse proportion?
The variables will always multiply together to get the same value.
What is the symbol for direct proportion?
∝
How is a compound interest graph notated?
y = ag^x where a is a coefficient, g is an unknown constant and x and y are the two variables.
How do you find the value of g in this case?
You look at the graph and find a case, e.g. when x is 2, y is 2,000. You notate it x = 2, y = 2,000. This means
2,000 = ag^2. We then divide by a and root it to get g.
How do you then find the function?
You simply plug in the value of g to get the function.
