◈ Oracle PrepSign Up Free
A-LevelMathematicsProbability and statistics9709/62 · Feb/Mar 2019 · Q24 Marks

For 40 values of the variable x, it is given that ∑(x − c)² = 3099.2, where c is a constant. The standard deviation of these values of x is 3.2.

  1. (i)Find the value of ∑(x – с).[3]
  2. (ii)Given that c = 50, find the mean of these values of x.[1]

Mark scheme

Marking points from the official mark scheme (Feb/Mar 2019). The mark or mark type is shown in brackets.

  1. [M1] Use correct formula with values substituted
  2. [M1] Rearrange to make their (Σ(x−c)/40)² the subject, unsimplified.
  3. [A1] Exact value, cao
  4. [B1FT] FT their (i)

Write your answer and get it marked

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.

Sign up free →

About this question

Topic
Probability and statistics, A-Level Mathematics (syllabus 9709). Structured question, 4 marks.
Source
A-Level Mathematics, Feb/Mar 2019 Paper 6 Variant 2, question 2.

Questions and mark schemes are from past examination papers and remain the copyright of the exam board. How Oracle Prep builds its content

Related Mathematics questions

Probability and statisticsFeb/Mar 20175m

It is found that 10% of the population enjoy watching Historical Drama on television. Use an appropriate approximatio…

Probability and statisticsFeb/Mar 20179m

A plate of cakes holds 12 different cakes. Find the number of ways these cakes can be shared between Alex and James i…

Probability and statisticsFeb/Mar 20179m

Pack A consists of ten cards numbered 0, 0, 1, 1, 1, 1, 1, 3, 3, 3. Pack B consists of six cards numbered 0, 0, 2, 2,…

DifferentiationFeb/Mar 20187m

The parametric equations of a curve are x = 2t + sin 2t, y = 1 – 2 cos 2t, for −½π < t < ½π.

Differential equationsFeb/Mar 20188m

The variables x and θ satisfy the differential equation x cos² θ (dx/dθ) = 2 tan θ + 1, for 0 ≤ θ < ½π and x > 0. It …

Numerical methodsFeb/Mar 20189m

By sketching suitable graphs, show that the equation e²ˣ = 6 + e⁻ˣ has exactly one real root.

← Browse all past-paper questions

© 2026 Oracle Prep