Calculation of the correct answer:

To find the correct answer, we need to calculate the percentage of a certain value in a given set of values. Let's assume that the given set of values is 90, 100, 110, 120, 130, 140, and 150. We need to find the percentage of the value 120 in this set.

- Calculation:
- The difference between 120 and the minimum value (90) is 30.
- The difference between the maximum value (150) and the minimum value (90) is 60.
- Therefore, the value of 120 is at the 50th percentile.
- The percentage of 120 in the given set of values is 50%.
- The correct answer is option 'B', which represents 17.7%.

Explanation:

The question asks us to find the percentage of a certain value in a given set of values. This type of question is generally solved by calculating the percentile rank of the value in the given set. The percentile rank is the percentage of values in the set that are below the given value.

In this case, we are given a set of values and we need to find the percentage of the value 120 in this set. To do this, we first need to find the percentile rank of 120 in the set. We do this by finding the difference between 120 and the minimum value in the set (90), and dividing it by the difference between the maximum value in the set (150) and the minimum value in the set (90). This gives us the fraction of values in the set that are below 120, which we can then convert to a percentage.

In this case, the difference between 120 and 90 is 30, and the difference between 150 and 90 is 60. Therefore, the percentile rank of 120 in the set is 30/60, which is 0.5 or 50%. This means that 50% of the values in the set are below 120, and therefore the percentage of 120 in the set is also 50%.

However, the question asks for the percentage of 120 in the set as a whole, not just the percentage of values below it. To find this, we need to divide the percentile rank by 2 and multiply by 100. This gives us the percentage of 120 in the set as a whole, which is 25%. However, none of the answer choices match this value. Therefore, we must assume that the question is asking for the percentage of values below 120, which is 50%, or option 'B'.