**Answer: 21 ft³**

<u>Step-by-step explanation:</u>

Let x represent the height of the box.

Then the 5 ft width of cardboard is (5 - 2x) when creating the box

and the 9 ft length of cardboard is (9 - 2x) when creating the box.

Volume = length x width x height

= (9 - 2x)(5 - 2x)(x)

= 45x - 28x² + 4x³

Using Calculus to solve for x, set the derivative equal to zero and use the quadratic formula to solve for x:

V' = 45 - 56x + 12x²

0 = 12x² - 56x + 45

x = 3.6, x = 1.0

Use those values to find the width, length, and volume:

height(x) × width (5 - 2x) × length (9 - 2x) = Volume

3.63 × -2.26*

1 × 3 × 7 = 21

*width cannot be negative so the height cannot be 3.63

Answer:

Kindly check explanation

Step-by-step explanation:

A common problem with most research designs is bias, which could be introduced win several ways one if which is the favored selection of certain variables rather than being randomized. In the scenario above, the sampling time frame introduces a bias into the design as the tune span of pesticide use does not allay with that of the exposure history of the respondent. Therefore an entire lifetime evaluation of one variable and just 20 years evaluation of the other introduces a sampling bias into the research design. Similarly, evaluation the type of pesticide usage over certain time period may need to be considered as the effect of very old pesticides may differ from those used very recently.