Answer: The proportion of oil tankers that had spills is
or 0.329.
Step-by-step explanation:
Since we have given that
Number of tankers is drawn = 474
Number of tankers did not have spills = 318
Number of tankers have spills = 474 - 318 = 156
Proportion of oil tankers that had spills is given by

Hence, the proportion of oil tankers that had spills is
or 0.329.
Research scientists use a standard practice called the _____ method to help them understand phenomena.
Answer:
96
Step-by-step explanation:
For this case we propose a system of equations. We have to:
x: Let the variable that represents the number of dimes
y: Let the variable that represents the number of quaters
We know that:
One dime equals 10 cents, $0.10
A quater equals 0.25 cents, $0.25
According to the statement we have:

We multiply the first equation by -0.10:

We have the following equivalent system:

We add the equations:

Approximately 3 quater coins

And two dimes
Answer:
3 quater
2 dimes