Statistics — Class 10 Maharashtra SSC Mathematics revision notes
A 4-page visual revision sheet for Statistics, written for Class 10 Maharashtra SSC Mathematics. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDFA preview of page 1 — all 4 pages open full size in the app.
Statistics in one look
three averages for grouped data, and the pictures that show a distribution at a glance
Grouped data, and the words it brings
when there are many observations they are collected into class intervals, such as 10 to 20 and 20 to 30
the frequency f of a class is how many observations fall in it
the class mark x is the midpoint of a class, found as lower + upper/2, and it stands in for every value in that class
the class size h is the width of a class, upper limit minus lower limit, and it is usually the same throughout
cumulative frequency is a running total of the frequencies, either from the top down or from the bottom up
grouping loses the individual values, so every average below is an estimate, not an exact figure
The three averages
mean, direct methodx = Σ f_ix_i/Σ f_i
mean, assumed mean methodx = A + Σ f_id_i/Σ f_i
mean, step deviation methodx = A + Σ f_iu_i/Σ f_i × h
median of grouped dataM = L + fracn/2 - cff × h
mode of grouped dataZ = L + f_1-f_0/2f_1-f_0-f_2 × h
the empirical relation between themZ = 3M - 2x
Which average, and when
the mean uses every observation, so it is the most complete, but a single extreme value pulls it badly
the median is the middle value once the data is ordered, so extreme values do not move it. Prefer it for incomes and similar skewed data
the mode is the most frequent value, and it is the only average that makes sense for non numerical data such as shoe sizes or favourite colours
the modal class is the class with the highest frequency, and the mode lies inside it
the median class is the class in which the cumulative frequency first reaches or passes n/2
The step deviation method in order
write the class marks x_i for every class, each the midpoint of its interval
choose an assumed mean A, usually the class mark near the middle of the table, and the class size h
compute u_i = x_i - A/h for each row, which gives small whole numbers such as -2, -1, 0, 1, 2
multiply each u_i by its frequency and total the column to get Σ f_iu_i
total the frequency column to get n = Σ f_i
substitute into x = A + Σ f_iu_i/n × h, remembering that h multiplies the whole fraction
Page 1 of 4. The full sheet, all 4 pages, opens free in the app.
These notes are not a standalone PDF. CapCompass plans Mathematics chapter by chapter against your real exam dates and free hours, and when the plan reaches Statistics the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.