Question

A study had a normal distribution with the median value as 200 and standard deviation 20.68% will fall between

• A. 160-240
• B. 170-230
• C. 180-220
• D. 190-210

Answer 1

The Correct Option is C

The normal distribution in this study has a median (also the mean for normal distribution) of 200. For a normal distribution, approximately 68% of the data falls within one standard deviation from the mean. We calculate this range using the given standard deviation of 20.

1. Find the range by subtracting and adding one standard deviation from the median:
   • Lower bound: \(200 - 20 = 180\)
   • Upper bound: \(200 + 20 = 220\)
2. The range of one standard deviation from the mean is 180 to 220, which contains approximately 68% of the data.

Options	Range
160-240	Does not align with one standard deviation
170-230	Does not align with one standard deviation
180-220	Matches one standard deviation range (Correct)
190-210	Inner range than one standard deviation

Thus, the correct option is 180-220.