Answer:
MArginal productivity: 
We can interpret this as he will reduce his time an <em>additional </em>0.0002 seconds for every <em>additional </em>yard he trains.
Step-by-step explanation:
The marginal productivy is the instant rate of change in the result for an increase in one unit of a factor.
In this case, the productivity is the time he last in the 100-yard. The factor is the amount of yards he train per week.
The marginal productivity can be expressed as:

where dt is the variation in time and dL is the variation in training yards.
We can not derive the function because it is not defined, but we can approximate with the last two points given:

Then we can interpret this as he will reduce his time an <em>additional </em>0.0002 seconds for every <em>additional </em>yard he trains.
This is an approximation that is valid in the interval of 60,000 to 70,000 yards of training.
Answer:
The Median should be 89.5
And the mean should be 69.75
I hope that helped
Part 1:
The table showing the decreasing debt is shown as follows:
![\begin{tabular} {|c|c|c|c|} Starting Balance&Interest Accrued&Payment&Closing Balance\\[1ex] \$1,853.42&\$22.39&\$400&\$1,475.81\\\$1,475.81&\$17.83&\$400&\$1,093.64\\\$1,093.64&\$13.21&\$200&\$906.85\\\$906.85&\$10.96&\$200&\$717.81\\\$717.81&\$8.67&\$200&\$526.48\\\$526.48&\$6.36&\$200&\$332.84\\\$332.84&\$4.02&\$200&\$136.86\\\$136.86&\$1.65&\$138.51&- \end{tabular}](https://tex.z-dn.net/?f=%5Cbegin%7Btabular%7D%0A%7B%7Cc%7Cc%7Cc%7Cc%7C%7D%0AStarting%20Balance%26Interest%20Accrued%26Payment%26Closing%20Balance%5C%5C%5B1ex%5D%0A%5C%241%2C853.42%26%5C%2422.39%26%5C%24400%26%5C%241%2C475.81%5C%5C%5C%241%2C475.81%26%5C%2417.83%26%5C%24400%26%5C%241%2C093.64%5C%5C%5C%241%2C093.64%26%5C%2413.21%26%5C%24200%26%5C%24906.85%5C%5C%5C%24906.85%26%5C%2410.96%26%5C%24200%26%5C%24717.81%5C%5C%5C%24717.81%26%5C%248.67%26%5C%24200%26%5C%24526.48%5C%5C%5C%24526.48%26%5C%246.36%26%5C%24200%26%5C%24332.84%5C%5C%5C%24332.84%26%5C%244.02%26%5C%24200%26%5C%24136.86%5C%5C%5C%24136.86%26%5C%241.65%26%5C%24138.51%26-%0A%5Cend%7Btabular%7D)
The column for interest accrued is obtained by the folmular

where P is the month's starting balance.
Part 2:
From the table, the last payment is $138.51
Part 3:
The total amount paid by the time the credit card is payed of is the summation of the "payment" column of the table.
Thus, the total amount is given by:

Part 4:
The debt ratio is given by
Answer:
JM = ML, LO = OK, and KN = NJ
Step-by-step explanation:
This makes the most sense.
For two objects with a finite constant mass, Fg is inversely proportional to the square of the distance between them. As r gets smaller the gravitational force increases. When the two objects are touching Fg is highest. But the mass of an object is focussed at its centre, the centre of mass. When the objects are touching their centres of mass are still separated. The graph has a vertical asymptote at r=0, implying an infinite gravitational force.