Nerf guns For a class project, a statistics student tested his theory about the regulators found on Nerf

Nerf guns For a class project, a statistics student tested his theory about the regulators found on Nerf guns: that they slow the muzzle velocity of the darts. He collected three Nerf guns that had 22 barrels among them, each barrel individually regulated. He fired a Nerf dart once using each barrel and measured how many inches it traveled, using the same dart on all tests. He then removed the regulators and fired one shot with each of the barrels again. The data he recorded appears below:

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a) Is this an observational study or an experiment?

b) If there is no difference between firing with and without a regulator, what percentage of all barrels would expect to fire a Nerf dart further without a regulator than with a regulator?

c) How many barrels actually fired further without a regulator?

d) Assuming that there really is no difference between using a regulator and not using a regulator, compute the probability of observing a result at least as extreme as the one observed here?

e) Are the results of this study unlikely to be observed by chance?

f) What can you conclude about the student's original question?