Refer to this link
For questions 1 through 3. Questions 4 through 6 build on them.
Unfortunately there isn't enough info to address question 4, so I'll skip it.
Question 5
We're now considering reaction time of the catcher. Also, we're adding in the pitcher's complete throwing motion duration. This timespan is 0.8+0.9 = 1.7 seconds
Recall back in problem 2, it takes about 0.96 seconds for the catcher to throw the ball to second base (i.e. throw the ball about 127 ft).
So overall, the ball goes from the pitcher to the catcher to the second base in 1.7+0.96 = 2.66 seconds approximately.
We'll compare this to the result of problem 3 (which was 3.039 seconds approximately)
Unfortunately for the runner, they will still not beat the ball. So the runner is still tagged out in this scenario.
The runner will not steal second base.
Question 6
The percentages tell the story. The lower percentage for second base tells us this base is harder to steal.
You may be wondering: why is third base easier to steal than second? This is a bit strange considering that third base is closer to the catcher compared to second base. Surely the catcher can throw to this location much faster, thereby tagging the runner out easier.
Well it all comes down to how far a lead the runner has. For first base, the runner has a shorter lead because the first baseman is pretty much very close to or on the first base. This baseman plays close to the foul line.
Meanwhile, the second baseman is a bit further from their base to fill in the infield gap on the right side (that is opposite the short stop). This allows a runner to get a bigger lead when they start at second base. Of course, the second baseman is still within striking distance just enough to be able to catch the ball and tag out any incoming runner from first base. They're also there to tag out any returning runner to this base (in the event they decide that stealing third is a bad idea). In other words, the second baseman isn't completely out in the middle of nowhere like the right outfielder is.
So to summarize: the runner has a longer lead when starting at second base, when compared to starting at first base.
Side note: it might help to get more familiar with the rules of baseball the best you can.
