CA Foundation · Quantitative Aptitude · Theoretical Distributions
The weights of packets filled by a machine in Surat follow a normal distribution with standard deviation 15 grams. Using the relationship between measures of dispersion in a normal distribution, what is the approximate quartile deviation?
The quartile deviation is about 10 grams. In a normal distribution the quartile deviation equals two-thirds of the standard deviation, so (2/3) × 15 = 10. The figure of 12 grams would be the mean deviation, which is four-fifths of the standard deviation.
- A12 grams
- B7.5 grams
- C22.5 grams
- D10 gramsCorrect
Explanation
For a normal distribution, quartile deviation = (2/3) × standard deviation. So QD = (2/3) × 15 = 10 grams. The figure 12 is the mean deviation, which is (4/5) × SD, and so is a different measure.
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