Unit 7 · Data and Percentage

School Library — Fiction Readers + Audiobook Fans

Lesson 3 of 3

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About this lesson

Now for the most demanding variant in this unit — a multi-layer calculation where you must work through five separate steps before reaching the final answer. One wrong step early on cascades into an incorrect total at the end.

Chapters

0:00Introduction
0:22The Question
1:19Determining Year 6's Population
1:44Calculating Checkouts per Year Group
2:10Exam Strategy – Tabular Organisation
2:34Finding the Non-Checkouts
2:53Applying Percentages and Finding the Final Answer

Question

A school library recorded checkouts for 3,600 students across four year groups.

  • Year 3 had 800 students, and 400 of them checked out a book.
  • Year 4 had 1,000 students, and 3 out of every 5 checked out a book.
  • Year 5 had 600 students, and 1 out of every 4 checked out a book.
  • Year 6 had the remaining students, and 7 out of every 8 checked out a book.

If 50% of students who checked out a book preferred fiction and 40% of students who did NOT check out a book preferred audiobooks, how many students were in these two categories combined?

How many students were in these two categories combined?

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