Answer:
B. Stratified random sample is the correct answer
in the first half he would have swam 1 km. there are 1000m in a km so 1000/200=5 so he swam the first 200 fly, then a 200 breast, then a 200 fly again, then another 200 breast the finish the first 1 km with a 200 fly. so we switched strokes 4 times.
PS i wouldn't recommend doing a 2 km swim fly and breast
The partial products would be 10 multiply 40, 10 multiply 3, 7 multiply 40, and 7 multiply 3.
Given cost function is
c(x) =
(20 ≤ x ≤ 400)
where x is the number of thousands of square feet
total revenue will be $0.2 million dollars per thousand square feet
Revenue is 0.2 millions per thousand square feet. we know x is the number of thousand of square feet
So R(x) = 0.2x
We know Profit = Revenue - Cost
P(x) = R(x) - C(x)


combine like terms

Profit function is
