Answer:
Part A. At least 6 hours
Part B. In less than 2.5 hours, Elijah will fall behind Mercedes
Part C. In over 2.5 hours, Elijah will lead Aubrey
Step-by-step explanation:
D = distance
v = speed
t = time
Formula connecting D, v, and t:
Part A.
Steve's speed: 
Distance: a minimum of 21 miles
Time: unknown, so
![3.5\cdot t\ge 21\\ \\35t\ge 210\ [\text{Multiplied by 10}]\\ \\t\ge \dfrac{210}{35}\\ \\t\ge \dfrac{30}{5}\\ \\t\ge 6](https://tex.z-dn.net/?f=3.5%5Ccdot%20t%5Cge%2021%5C%5C%20%5C%5C35t%5Cge%20210%5C%20%5B%5Ctext%7BMultiplied%20by%2010%7D%5D%5C%5C%20%5C%5Ct%5Cge%20%5Cdfrac%7B210%7D%7B35%7D%5C%5C%20%5C%5Ct%5Cge%20%5Cdfrac%7B30%7D%7B5%7D%5C%5C%20%5C%5Ct%5Cge%206)
It would require Steve a minimum of 6 hours to traverse at least 21 miles on Day 1.
Part B.
Mercedes's speed: 
Elijah's speed: 
Elijah's Distance walked: 
miles
Mercedes's Distance walked: 
miles
Time: x hours
Mercedes is 2 miles ahead, therefore
Elijah will trail behind until
In 2.5 hours, Elijah will close the gap on Mercedes, and in less than 2.5 hours, Elijah will trail behind her.
Part C.
Aubrey's speed: 
Elijah's speed:
Elijah's Distance walked: miles
Aubrey's Distance walked: 
miles
Time: x hours
At the beginning of Day 3, Elijah starts from Mile 42, while Aubrey begins at Mile 42.5.
Elijah will be ahead of Aubrey when
![D_E>D_A\\ \\42+3.2x> 42.5+3x\\ \\3.2x-3x>42.5-42\\ \\0.2x>0.5\\ \\2x>5\ [\text{Multiplied by 10}]\\ \\x>\dfrac{5}{2}\\ \\x>2.5\ hours](https://tex.z-dn.net/?f=D_E%3ED_A%5C%5C%20%5C%5C42%2B3.2x%3E%2042.5%2B3x%5C%5C%20%5C%5C3.2x-3x%3E42.5-42%5C%5C%20%5C%5C0.2x%3E0.5%5C%5C%20%5C%5C2x%3E5%5C%20%5B%5Ctext%7BMultiplied%20by%2010%7D%5D%5C%5C%20%5C%5Cx%3E%5Cdfrac%7B5%7D%7B2%7D%5C%5C%20%5C%5Cx%3E2.5%5C%20hours)
In 2.5 hours, Elijah will surpass Aubrey, and after more than 2.5 hours, Elijah will outpace Aubrey.
Let Jacob, Carol, Geraldo, Meg, Earvin, Dora, Adam, and Sally be denoted as J, C, G, M, E, D, A, and S respectively. In part IV, we need to identify the pairs of potential clients that could potentially be selected. The sample space consists of all possible outcomes, therefore we create a set of all valid pairs, listed as follows: {(J, C), (J, G), (J, M), (J, E), (J, D), (J, A), (J, S), (C, G), (C, M), (C, E), (C, D), (C, A), (C, S), (G, M), (G, E), (G, D), (G, A), (G, S), (M, E), (M, D), (M, A), (M, S), (E, D), (E, A), (E, S), (D, A), (D, S), (A, S)}. We can verify the number of elements in the sample space, n(S) is 1+2+3+4+5+6+7=28. This gives us the answer to the first question: What is the count of pairs of potential clients that can be randomly selected from the pool of eight candidates? (Answer: 28.) II) What is the chance of a certain pair being chosen? The chance of picking a specific pair is 1/28, as there’s just one way to select a particular pair out of the 28 possible options. III) What is the probability that the selected pair consists of Jacob and Meg or Geraldo and Sally? The probability of selecting (J, M) or (G, S) is 2 out of 28, which equates to 1/14. Answers: I) 28 II) 1/28 ≈ 0.0357 III) 1/14 ≈ 0.0714 IV) {(J, C), (J, G), (J, M), (J, E), (J, D), (J, A), (J, S), (C, G), (C, M), (C, E), (C, D), (C, A), (C, S), (G, M), (G, E), (G, D), (G, A), (G, S), (M, E), (M, D), (M, A), (M, S), (E, D), (E, A), (E, S), (D, A), (D, S), (A, S).}
