The mean of a data set  is equal to the sum of the terms divided by the number of terms, which here is 9. Therefore,

The median of a data set with an odd number of terms is the term that falls in the middle when the terms are ordered. The terms are already ordered:

so the element that falls in the middle is 12.

The mode of the data set is the term that occurs most frequently, which is 12.

The midrange is the mean of the least and greatest elements, which is

.

Of the four - mean, median, mode, and midrange - the median and the mode are equal.

The mean of a data set  is equal to the sum of the terms divided by the number of terms, which here is 9. Therefore,

The median of a data set with an odd number of terms is the term that falls in the middle when the terms are ordered. The terms are already ordered:

so the element that falls in the middle is 12.

The mode of the data set is the term that occurs most frequently, which is 12.

The midrange is the mean of the least and greatest elements, which is

.

Of the four - mean, median, mode, and midrange - the median and the mode tie for being the least.

From the question, we know the average age from a random sample of 50 people was 28.5 years; however, because this data is only from a random sampling of people, it is difficult to say anything certain about the entire population.

While it seems that the previously reported age is wrong, and that the average age of people on the island is likely around 29, it is impossible to say for certain what the average age actually is without gathering data for every single person on the island. 

With findings from a random sample, you can draw conclusions about what is likely.

It is likely that the actual average age is lower than the previously reported average age; however, without data for every single person in the population, statements that are certain, such as, "The average age of the indigenous people on the island is 28.5 years," cannot be made.

Note that the statement, "The average age of indigenous people on the island is between 28 and 29 years," is a certain statement, even though it does not give an exact value for the average. Even though researchers found an average age of 28.5 years, it is still very possible that the actual average age is outside the range of 28 to 29. 

Therefore, the statement, "It is very likely that the average age of people on the island is actually much lower than previously reported," is the answer because it does not try to make any certain claims and the conclusion is supported by the findings.

From the question, we know that 60 out of a random sample of 80 locations experienced increased sales in the last two weeks; however, because this data is only from a random sampling of locations, it is difficult to say anything absolute about the population (all of the locations).

While 75% of the random sample did experience increased sales, we cannot know for certain what portion of the entire population experienced increased sales. What we can conclude from this data is that it is likely that the percentage of restaurants that experienced increased sales is roughly around 75%. 

Therefore, the statement that can be made with the most certainty is that "It is very likely that more than half of all franchise locations experienced increased sales in the last two weeks."