If the center is at (0, 0) and the vertex is at (20, 0), then the distance, a, is the length from the center to the vertex, 20. The distance from the center to the focus is c. The distance from the center to the focus is 16, so c = 16. The formula we use to find the focus is

. We have our c value and our a value, so we will sub in those to find b.

and 256 = 400 - b^2. -b^2 = -144, so b = 12. There you go!
The answer is:
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[A]: Erin Naismith lives in Springfield, Massachusetts.
Answer:
Kristi
Step-by-step explanation:
The formula for Simple Interest =
Principal × Rate × Time
For Kristi
Kristi invests $3,000 at a 7.25% annual simple interest rate,
Principal = $3000
Rate = 7.25% = 0.0725
Time = 1
Simple interest = $3000 × 0.0725 × 1
= $217.5
For Kari
Her sister Kari invests $3,200 at a 6.25% annual simple interest rate.
Principal = $3200
Rate = 6.25% = 0.0625
Time = 1
Simple interest = $3200 × 0.0625 × 1
= $200
From the above calculation, we can see that: Kristi will earn the greater amount of interest after one year
I=Prt
I=$1,200(0.04)3
I=$144
This question is incomplete.
The complete question says;
The two-way table shows the number of hours students studied and whether they studied independently or with a study group.
What is the relative frequency of students that studied independently for more than 2 hours to the total number of students that studied independently?
a) 0.4 c) 0.25
b) 0.33 d) 0.11
Table is attached as image
Answer: C (0.25)
The number of students that studied for more than 2 hours as given in the table are 4.
The total number of people that studied independently include those that studied less than 2 hours and those that studied for more than 2 hours.
Those that studied less than 2 hours independently are 12.
Those that studied more than 2 hours independently are 4.
Hence the total number of people that studied independently is 16.
Therefore the relative frequency of students that studied independently for more than 2 hours to the total number of students that studied independently would be = 4/16 = 1/4 = 0.25.