Question

What do you mean by precision?

Answer 1

Hint: Closeness to the measured value or the sharpness in measuring. There is a difference between accuracy and precision. A value or group of values can be accurate but not precise or vice versa. Keep this in mind when thinking of precision.

Complete step by step solution:
Precision is the closeness of values to each other whereas accuracy is the closeness of the value to the true value.
Suppose you have a dartboard, and you throw darts at it. The center point which is also called the bull’s eye is your ultimate target and then concentric rings have different points when you hit them. You throw 5 darts at the board and 1 of them hits the center point and the other 4 hits around the, say 20 points circle. The first dart that you threw is very accurate and the 4 other darts that hit one around each other are very precise. If all of those darts hit the center point then they are said to be precise and accurate at the same time.
For measuring a long notebook using this scale properly gives you the precise value. The length of the notebook has crossed the 15 cm mark (main marks). Which means the length of the notebook is almost 15cm. But reading the smaller markings (which are 1/10th of the main marking) we see that the length of the notebook crosses the 7th mark. This gives us more precise reading saying that the length is almost 15.7 cm. This measurement is more precise than the 15cm measurement.
Now just so that we know, the scale can be completely wrong. I may be showing 2 cm as 1.5 cm. Which means that although the measurement is precise to the first decimal place, the measurement has bad accuracy.

Note: Precision doesn't necessarily mean that the experiment was successful. For an experiment to be successful its values should be both precise and accurate.