Question

PLEASE HELP THERE ARE TWO PARTS!!

The graph shows the relationship between the United States dollar and
the euro, the currency of the European Union, in December 2011. Part A:
What is the constant of proportionality shown in the graph? *
Exchange Rate (December 6, 2011)
VA
(400, 300)
300
Number of euros
200
(250, 187.50)
100
(120,90)
100 200 300
400
Number of US dollars
I

Answer 1

The constant of proportionality of the graph is 0.75

Explanation:

The coordinates of the points on the lines are;

(400, 300), (250, 187.5), and (120, 90)

Which can be written in a tabular form as follows;

Number of US dollars
`{}` Number of euros

120
`{}` 90

250
`{}` 187.5

400
`{}` 300

Given that the graph is a straight line graph, we can represent the graph with the straight line equation, y = m·x + c

Where;

c = The y-intercept (where the graph meets the y-axis) = 0

m = The slope = The constant of proportionality

`Slope, \, m =(y_(2)-y_(1))/(x_(2)-x_(1))`

`m =(300-90)/(400-120) = (210)/(280) = 0.75`

We have, y = m·x = 0.75·x.

Therefore, the constant of proportionality of the graph = 0.75.