Data & Probability · Apply · 4.2

Averages in real life.

Means show up everywhere — average test scores, average daily temperature, average price. The method is the same: total the values and divide by the count, then interpret the result in context.

01 / THE IDEA

See it work.

The data

See the values.

151182123154

Watch the method

Averages in real life

Real averages: total ÷ count, then interpret.

1 / 2
Find the mean of: 15, 18, 12, 15.
1

Add the values

Find the total of every value in the set.

15+18+12+15=6015 + 18 + 12 + 15 = 60
2

Divide by how many

The mean is the total divided by the number of values.

604=15\frac{60}{4} = 15
02 / YOUR TURN

Practice until it feels automatic.

Your turn

Work it out.

Type the answer — a fraction or decimal is fine.

streak 0
best 0

…

— / WHY IT WORKS

The idea underneath.

Numbers from life

Real data still follows total ÷ count for the average.

Why it works

Same recipe, real ingredients.

03 / WORKED EXAMPLES

From easy to tricky.

EX 1easy

Find the mean of: 5, 2, 5, 2.

1

Add the values

Find the total of every value in the set. 5 + 2 + 5 + 2 = 14

2

Divide by how many

The mean is the total divided by the number of values. 14/4 = 7/2

EX 2medium

Find the mean of: 8, 9, 9, 7.

1

Add the values

Find the total of every value in the set. 8 + 9 + 9 + 7 = 33

2

Divide by how many

The mean is the total divided by the number of values. 33/4 = 33/4

EX 3hard

Find the mean of: 11, 8, 9, 2, 6, 4.

1

Add the values

Find the total of every value in the set. 11 + 8 + 9 + 2 + 6 + 4 = 40

2

Divide by how many

The mean is the total divided by the number of values. 40/6 = 20/3

04 / COMMON TRAPS

Where students slip.

Trap

Ignoring units.

Fix

Keep the units (points, °, $) on the answer.

Trap

Skipping the divide.

Fix

It’s still total ÷ count.

05 / QUIZ

Test yourself.

The Test

12 problems across three tiers. Auto-graded on submit. Hints and a full walkthrough on every question. Your work is saved on this device — sign in to keep it across devices.

0/12Answered
How to answerType just the value. Formatting won't trip you up — we ignore spaces, capital letters, commas, and subscript style, so t₁ = 5, d = 3 and t1=5,d=3 both count. For a list of numbers, separate them with commas (e.g. 3, 10, 17).
Core

Core (4)

C1

Find the mean of: 2, 5, 8, 9, 8, 6.

Need a hint?
  • Add the real values.
  • Divide by how many.
C2

Find the mean of: 8, 11, 11, 3.

Need a hint?
  • Add the real values.
  • Divide by how many.
C3

Find the mean of: 7, 8, 9, 5, 4.

Need a hint?
  • Add the real values.
  • Divide by how many.
C4

Find the mean of: 11, 11, 8, 3.

Need a hint?
  • Add the real values.
  • Divide by how many.
Apply

Apply (4)

A1

Find the mean of: 6, 8, 2, 10, 3, 11.

Need a hint?
  • Add the real values.
  • Divide by how many.
A2

Find the mean of: 11, 5, 3, 12.

Need a hint?
  • Add the real values.
  • Divide by how many.
A3

Find the mean of: 7, 11, 7, 2, 4.

Need a hint?
  • Add the real values.
  • Divide by how many.
A4

Find the mean of: 5, 7, 5, 10, 5, 3.

Need a hint?
  • Add the real values.
  • Divide by how many.
Extension

Extension (4)

E1

Find the mean of: 3, 11, 9, 9, 10.

Need a hint?
  • Add the real values.
  • Divide by how many.
E2

Find the mean of: 3, 11, 11, 5.

Need a hint?
  • Add the real values.
  • Divide by how many.
E3

Find the mean of: 11, 2, 4, 2, 11.

Need a hint?
  • Add the real values.
  • Divide by how many.
E4

Find the mean of: 9, 11, 4, 6.

Need a hint?
  • Add the real values.
  • Divide by how many.