Lesson 6 of 9
One try can fool you
Show on a big screenYou time a rolling marble once: 4.2 seconds. Is that the answer?
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Step 1 of 4
- Trial 1 is one try. It is far from the real value.
- More trials fall on both sides of the real value.
- Their average is close to the real value.
- One try can mislead. The average of many is closer.
Not yet, because one try can be wrong.
Trial — one try of a test.
Rule: Repeat a test many times. Then take the .
Average — the total of all trials ÷ the number of trials.
Example: 1 takes 4.2 seconds. Trial 2 takes 3.4 seconds.
Total: 4.2 + 3.4 = 7.6 seconds.
: 7.6 ÷ 2 = 3.8 seconds, for 2 .
Try the lab to finish this lesson.