To solve: the proportion 17z=810 for z.

Question

stuth1 · Accepted Answer

Approach:
If two ratios are equal then it is a proportion. If

\frac{p}{q}

and

\frac{r}{s}

are two ratios, then

\frac{p}{q} = \frac{r}{s}

is a proportion.
Ex:

\frac{3}{4} = \frac{15}{20}

For finding unknown numbers in proportions, we use cross product to find the unknown number.
Ex:

\frac{2}{7} = \frac{x}{14}

Here in the example x is the unknown number. To calculate the value of x, we use the cross product.
Calculation:
Given

\frac{17}{z} = \frac{8}{10}

Apply the cross product in order to find the unknown number.

17 \times 10 = z \times 8

170 = 8 z

Divide both the sides by 8

\frac{170}{8} = \frac{8 z}{8}

21.25 = z

or

z = \frac{85}{4}

Final statement: The solution for the proportion

\frac{17}{z} = \frac{8}{10}

for the indicated variable is

z = \frac{85}{4}

or

z = 21.25

To solve: the proportion \frac{17}{z}=\frac{8}{10} for z.