It takes 4.3 seconds for the rocket to return to earth.
The equation is:

where -9.8m/sec² is the acceleration due to gravity, v₀ is the initial velocity, and h₀ is the initial height. We will go from the assumption that the rocket is launched from the ground, so h₀=0, and we are told that the initial velocity, v₀, is 42. This gives us:

We will use the quadratic formula to solve this. The quadratic formula is:

Plugging in our information we have:

x=0 is when the rocket is launched; x=4.3 is when the rocket lands.
A square of area 121 ft² will have a side dimension of √121 ft = 11 ft. The perimeter is the length of 4 sides, so is 44 ft.
Answer:
His overal final score is 81.2. His letter grade is a B.
Step-by-step explanation:
Weighed average:
The sum of all values multiplied by it's weight. The weight is a proportion(a value between 0 and 1).
So.
Score of 72 on the midterm, which counts 5%.
Score of 83 on the project score, which counts 25%.
Score of 91 on homework assignments, which counts 35%.
Score of 74 on the final exam, which counts 35%.
His grade is:
G = 72*0.05 + 83*0.25 + 91*0.35 + 74*0.35 = 82.1.
His overal final score is 81.2.
At least 80 but less than 90 is a B
So his letter grade is a B.
1. D
2. D
I don't know the answer to number 3 sorry.