Statistics Level 2 Practice: Mean, Median, Mode and Frequency-Table Questions
Students who are comfortable with basic averages and want medium-level practice will find this Level 2 Aptitude360 set useful. It covers mean, median and mode in harder settings: combined means, frequency tables with a missing value, the empirical relation with decimals, coefficient of range, and variance and standard deviation. Worked solutions are given for every question.
What the Level 2 mean, median and mode questions test
- Replacing, removing or adding observations and finding the changed mean
- Correcting a mean after more than one value was copied wrongly
- Combined mean of two groups and the required score for a target average
- Median of unsorted data and median from a discrete frequency table
- Finding a missing frequency or an unknown value from a given mean or median
- Empirical relation between mean, median and mode, including differences between them
- Coefficient of range, variance, standard deviation and sum of squares from mean and variance
- Linear transformation of data, including multipliers less than zero
Important formulas and rules for Level 2
- Combined mean: \( \dfrac{n_{1}\bar{x}_{1}+n_{2}\bar{x}_{2}}{n_{1}+n_{2}} \)
- Coefficient of range: \( \dfrac{L-S}{L+S} \)
- Variance shortcut: \( \sigma^{2}=\dfrac{\sum x^{2}}{n}-\bar{x}^{2} \)
- Mean minus mode: \( \bar{x}-\text{Mode}=3(\bar{x}-\text{Median}) \)
- If \( y=ax+b \): \( \sigma_{y}^{2}=a^{2}\sigma_{x}^{2} \)
How to prepare for medium-level statistics problems
- Rearrange the variance shortcut to get the sum of squares when mean and variance are given.
- In a frequency table, build cumulative frequencies before locating the median.
- For a missing frequency, write the mean equation with the unknown in both the numerator and the total frequency.
- Under a linear change, the new mean is the multiplier times the old mean plus the added constant, while the standard deviation is multiplied by the absolute value of the multiplier.
Who this Level 2 set suits
It suits aptitude aspirants who have finished the basic level and want stronger practice before moving to the hardest statistics problems.