Original practice
Mark points shown after marking
A graph point sits about halfway between 2.0 and 2.4 on the y-axis. Estimate its y-value.
(1)Total for this question: 1 mark
COMMAND WORD · BIOLOGY
Estimate
Give an approximate value, show what you approximated, and do not add precision you do not have.
Method
The rough reading, then the rough working, then an answer that still says about.
What the parts mean
- Readingthe length or point you judged by eye
- Workingthe simple route, with the rounding visible
- Answera value that does not look finer than the reading
How to build your answer
- 1Say what you are treating as approximate.
- 2Show the rough working.
- 3Keep the word about, and drop extra decimal places.
Biology exemplar
Original question
A 10 µm scale bar is about 20 mm long on the page. A nucleus is about 10 mm long. Estimate its actual length.
Annotated answer
ReadingAbout 20 mm represents 10 µm. WorkingAbout 10 mm represents 5 µm. AnswerThe nucleus is about 5 µm long.
The labels match the frame. Read them in order. This is one accurate route, not the only one.
Exam habit
If you say about, do not then write three decimal places.
Common pitfall
Writing 5.000 µm, as if the estimate had been measured exactly.
Practice question
Answer discussion
Halfway from 2.0 to 2.4 is about 2.2. That is the estimate. 2.20 pretends you read the point more finely than “about halfway”.