Edexcel IAL S1 Measures of Location and Spread Questions
Mean, median, mode, quartiles and percentiles (incl. interpolation), variance and standard deviation; coding.
- S1 · Statistics 1
- Calculator allowed
- 30 practice questions
What the questions test
The 30 S1 measures of location and spread practice questions cover:
Worked example 1
For a sample of $n=10$ observations, $\Sigma x = 120$ and $\Sigma x^2 = 1800$. A new variable $y$ is defined as $y = 3x - 2$. Calculate the mean and variance of $y$.
Mark scheme
- M1 for calculating $\bar{x} = \frac{120}{10} = 12$.
- M1 for finding $\bar{y} = 3(12) - 2 = 34$.
- M1 for calculating $Var(x) = \frac{1800}{10} - 12^2 = 180 - 144 = 36$.
- M1 for applying the variance transformation rule $Var(y) = 3^2 \times Var(x)$.
- A1 for finding $Var(y) = 9 \times 36 = 324$.
Worked example 2
A dataset $x$ has mean $\bar{x} = 5$ and standard deviation $\sigma_x = 2$. A new dataset $y$ is formed using the linear transformation $y = ax + b$, where $a > 0$. The new dataset has mean $\bar{y} = 15$ and standard deviation $\sigma_y = 6$. Find the values of $a$ and $b$.
Mark scheme
- M1 for linking the standard deviations: $\sigma_y = a \sigma_x$.
- A1 for solving for $a$: $6 = a(2) \implies a = 3$.
- M1 for linking the means: $\bar{y} = a\bar{x} + b$.
- A1 for substituting $a=3$ to find $b$: $15 = 3(5) + b \implies b = 0$.
FAQ
What measures of location and spread is in Edexcel IAL S1?
Mean, median, mode, quartiles and percentiles (incl. interpolation), variance and standard deviation; coding.
Is S1 a calculator paper?
Yes, a calculator is allowed in S1, but method marks are only given for working you write down.
How are S1 measures of location and spread questions marked?
With M marks for a correct method, A marks for accurate answers that depend on the M mark before them, and B marks for independent results, as in the worked examples on this page.