Identify the level of measurement of the​ data, and explain what is wrong with the given calculation.
In a set of​ data, mood levels are represented as 10 for bad, 20 for OK, and 30 for good. The average​ (mean) of the 672 mood levels is 25.4.

The data are at the _______level of measurement.

a. Nominal
b. Ordinal
c. Interval
d. Ratio