Mean, Median and Mode Level 3: Hard Statistics Problems with Solutions
Grouped-data mean and mode, rescaled scores, coefficient of variation and multi-step corrections to averages form the core of this Level 3 statistics set. It is the advanced Aptitude360 practice quiz on mean, median and mode, where most questions need two or more steps and some combine several measures. Each question has a worked solution.
Topics in this advanced mean, median and mode set
- Corrected mean after several wrong entries and averages after members join or leave
- Mean of class-interval data using class midpoints, and missing frequencies with a known total
- Mode of grouped data using the modal class formula
- Median after observations are added or struck off
- Using mean, median and mode together with unknowns in the data
- Variance, standard deviation, and recovering missing observations from mean and variance
- Rescaling test scores linearly and finding the coefficient of variation of a transformed variable
- Range of combined sets and extreme values under mean and median constraints
Advanced formulas for statistics problems
- Grouped mode: \( l+\dfrac{f_{1}-f_{0}}{2f_{1}-f_{0}-f_{2}}\times h \)
- Grouped mean: \( \bar{x}=\dfrac{\sum f_{i}m_{i}}{\sum f_{i}} \)
- Coefficient of variation: \( \dfrac{\sigma}{\bar{x}}\times 100 \)
- Sum of squares: \( \sum x^{2}=n(\sigma^{2}+\bar{x}^{2}) \)
- Squares of first \( n \) naturals: \( \dfrac{n(n+1)(2n+1)}{6} \)
Revision tips for hard statistics questions
- Track the total sum through every change, since most average problems reduce to fixing the total.
- For grouped mode, identify the modal class by highest frequency and read the neighbouring frequencies carefully.
- Adding an observation equal to the mean keeps the mean fixed and lowers the variance whenever the original variance is positive, so recompute using the sum of squares.
- To maximise one value under a mean and median condition, keep the other values as small as the conditions allow.
Who should take Level 3
Aspirants who have completed the earlier levels and want tough, multi-step statistics practice for quantitative aptitude should take this set.