Try to express how many percent of the donuts in the box that have pink sprinkles using proportions.
$$\frac= \frac$$ $$\frac\cdot = \frac\cdot 8$$ $\cdot 100= \frac\cdot $$ $$\frac=\frac$$ $$x=25\%$$ This proportion is called the percent proportion.
Percent is a ratio were we compare numbers to 100 which means that 1% is 1/100.
Example In a box of eight donuts two have pink sprinkles.
$$\frac=\frac$$ $$\frac\cdot =\frac\cdot y$$ $$x\cdot b=\frac\cdot y$$ $$xb=ay$$ The products xb and ay are called cross products.
The cross products of a proportion are always equal.
$$\frac,\: \: \frac$$ $$\frac\overset \frac$$ $$\frac\cdot 16\cdot 40\overset \frac\cdot 16\cdot 40$$ $$\frac\cdot\cdot 40\overset \frac\cdot 16\cdot $$ $\cdot 40\overset5\cdot 16$$ $=80$$ Here we can see that 2/16 and 5/40 are proportions since their cross products are equal.
Percent means hundredths or per hundred and is written with the symbol, %.
Example Use cross product to determine if the two ratios form a proportion.It’s helpful to understand how these percents are calculated.Jeff has a coupon at the Guitar Store for 15% off any purchase of 0 or more.Jeff wonders how much money the coupon will take off of the 0 original price Percent problems have three parts: the percent, the base (or whole), and the amount.Any of those parts may be the unknown value to be found.To do this, think about the relationship between multiplication and division.Look at the pairs of multiplication and division facts below, and look for a pattern in each row.With percent problems, one of the ratios is the percent, written as Incorrect.You probably put the amount (18) over 100 in the proportion, rather than the percent (125).In fact we always use the same label of when we set ours up. So they are easier to compare than fractions, as they always have the same denominator, 100. The amount saved is always the same portion or fraction of the price, but a higher price means more money is taken off.