Answer:
A = 100 
Step-by-step explanation:
You have to use the area of a trapezoid formula:
A =
(a + b)
Now, substitute the values of the height and the bases:
A =
(10 + 15)
Finally, simplify the equation to solve for the area:
A = 4(25)
A = 100 
C, E, and F have 50 50 chance
X represent the number of laps Marcy swam, 114x represent the number of times Toni swam.
20 + 0.80(114x) + 15 + 0.85x = 257
20 + 91.2x + 15 + 0.85x = 257
92.05x + 35 = 257
Required equation is 92.05x + 35 = 257
A.

The denominator of the second number goes down one because you aren't replacing the initial marble pulled, making the amount of marbles in the bag go down, but not affecting the white count because you pulled a purple marble.
b.

The same can be said about the denominator for this problem, but not the numerator. The numerator must go down one number as well, because you already chose one white marble, taking one of the white marbles out of the bag, leaving you with one solitary, white marble.
c.
Chance of selecting two purple marbles:
<u />

Chance of selecting two white marbles:

<u>Chance of selecting two purple</u> vs. <em>Chance of Selecting 2 white:</em>
<u>0.583</u>><em>0.278</em>.
It is more likely to select 2 purple marbles.
Hope this helps!
This is called the Pythagorean theorem : a ² + b ² = c ². You can substitute any of the variable with any of the known numbers and then you all you have to do is isolate the variable. I hope that helps!!