The biologist should use a block design because the different types of bacteria may respond differently to the treatments.
I will determine the domain later
Bell:
1 hour = 10 miles
4.5 hours = 10 x 4.5 = 45 miles.
Kristin:
1 hour = 14 miles
4.5 hours = 14 x 4.5 = 63 miles
Difference in distance = 63 - 45 = 18 miles.
Answer: They will be 18 miles apart.
300 x 700 = 210,000 square feet
600 x 1400 = 840,000 square feet
840,000 - 210,000 = 630,000 square feet difference