Given the following sample of coating thickness measurements (in millimeters) for low-viscosity paint: $0.83$, $0.88$, $0.85$, $0.90$, $0.87$, $0.86$, $0.89$, what is the sample mean thickness as calculated using a graphing calculator (rounded to two decimal places)?

• A. $0.85$
• B. $0.87$
• C. $0.88$
• D. $0.89$

Answer: (B)

Verified step by step guidance

1. Identify the data points given: 0.83, 0.88, 0.85, 0.90, 0.87, 0.86, 0.89.
2. Recall that the sample mean \( \bar{x} \) is calculated by summing all the data points and then dividing by the number of data points. The formula is: \[\bar{x} = \frac{\sum_{i=1}^n x_i}{n}\] where \( x_i \) are the individual measurements and \( n \) is the total number of measurements.
3. Calculate the sum of all the measurements: add 0.83 + 0.88 + 0.85 + 0.90 + 0.87 + 0.86 + 0.89.
4. Count the number of measurements, which is 7 in this case.
5. Divide the sum obtained in step 3 by 7 to find the sample mean, then round the result to two decimal places as requested.