Final answer:
The K value mentioned in the error bound formulas for the midpoint, trapezoid, and Simpson's rule is calculated by subtracting the lower value from the upper value of the confidence interval and then dividing the difference by 2.
Step-by-step explanation:
The K value mentioned in the formulas is the upper value for the confidence interval minus the lower value, divided by 2. It represents the error bound for the midpoint, trapezoid, and Simpson's rule.
For example, if the upper value for the confidence interval is 10 and the lower value is 5, the K value would be (10 - 5) / 2 = 2.5. This means that the error bound for the calculations using these methods would be 2.5.
Increasing the confidence level requires increasing either the error bound or the sample size. So, if the firm needs to increase the confidence level, they would need to survey more than 206 people.