As you increase the subintervals the area will be closer and closer to the real value. In other words your approximation gets better.
As you increase the intervals, there will be more rectanagles and the added area of these rectangles are converging towards the actual area under the curve.
121 is big enough to assume normality and not worry about the t distribution. By the 68-95-99.7 rule a 95% confidence interval includes plus or minus two standard deviations. So 95% of the cars will be in the mph range

The question is a bit vague, but it seems we're being asked for the 95% confidence interval on the average of 121 cars. The 121 is a hint of course.
The standard deviation of the average is in general the standard deviation of the individual samples divided by the square root of n:

So repeating our experiment of taking the average 121 cars over and over, we expect 95% of the averages to be in the mph range

That's probably the answer they're looking for.
Answer:
The answer to your question is x – 56.64 = 3.36; x = 60 because He gave the cashier 60 dollars, and the cashier game him back 3.36 dollars. And 60-$56.64 = $3.36.
Step-by-step explanation:
Out of these four elements, Sovereignty stands accepted as the most important and exclusive element of the State. No other organisation or institution can claim sovereignty. An institution can have population, territory and government but not sovereignty. ... These are also loosely called states.
Answer: Trapezoid
Step-by-step explanation:
Trapezoids are parollelograms, that’s all