Why is it that when testing density of pennies , the more pennies u use, the more reliable the results?

Question

50 ml graduate cylinder has an error of about +.2 whatever that means??

Answer 1

In any experiment, the more data you gather, the more accurate your results.

Answer 2

To get an average. Pennies outer coating oxidizes, which changes the weight. '+.2' probably means +/- .2 of whatever unit you're using. Its called 'uncertainty'.

Answer 3

+/- 0.2 is the accuracy of the cylinder. That means that any reading that you take from it is accurate within 0.2ml. So, lets say you put water in it and the meniscus is exactly at 35ml. That means that the true amount is between 34.8 and 35.2 ml.

Whenever you test anything, the more items that you test, the more accurate your results. Since pennies these days are nickel coated in copper, a single penny may have slightly more or less copper or nickel than the average, so the density will vary. If you take the densities of multiple pennies, you will get to the real average, and the more tests you take the less you have to consider slight variations.