The is answer is definitely D, because he computed the total population of 3,320 in the survey of his targeted people that he specified which was grade school and high school. In order for his computation to work for his market analysis he used the radius of 5m and the 75% he wanted to achieve.
Part (b)
We use the result of part (a) and plug in (x,y) = (0,0). This is directly from the initial condition y(0) = 0.

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This means,

is the solution with the initial condition y(0) = 0.
Part A: 6w + 12 = 5w + 15
Part B: 6(8) + 12 = 5(8) + 15
48 + 12 = 40 + 15
60 = 55 = Company B equals $55 which is less than $60
Part C: $5 is saved because of the amount of money.
Hope this helps :)
Math answers to fraction 2356 divided by 27 can be calculated as follows.
2356/27 math problems division = 87.2592592593. Therefore 87.2592592593 to 2 decimal places= 87.26
2356/27 divided by 2 » (2356/27) ÷ 2 » 87.2592592593 ÷ 2 = 43.6296296296 .