Answer:
The average age of pilots has a lower coefficient of variation, so it is the most consistent data set.
Step-by-step explanation:
The coefficient of variation is used to measure consistency of a data set. It is the standard deviation divided by the mean. The higher the coefficient of variation, the more variable, that is, the least consistent the data set is.
The average number of newspapers for sale in an airport stand is 15. SD is 6.
The consistency is:

The average age of the pilots is 36 and SD is 4.
The consistency is:

The average age of pilots has a lower coefficient of variation, so it is the most consistent data set.
Is a calculator allowed? 8/13 = 0.61538. Then take arccos of that to get 52 degrees. Arccos on a calculator might be seen as acos or inv-cos.
Answer:
40.021
Step-by-step explanation:
Unlimited calls = $40
Text message = $0.021
NOTE:There is a difference between the value you gave for cost of text messages in the question and the values given in the group of answers. I will use $0.021 for cost of text messages since it is common to all answer choices.
Total cost = Cost of unlimited calls + cost of text messages
C = $40 + $0.021
= $40.021
Therefore, the equation which represent the total cost in dollars for a month is 40.021
A. 40.021