Sam is planning to open a dockless scooter company in Fayetteville and wants to estimate the amount of time a typical user would rent one. She visits a similar college town to investigate, where she randomly samples 20 customers and asks each to report the number of minutes the scooter was used. The average rental time was 142.21 minutes. Sam knows from national data that scooter rental time is a normally distributed variable with a standard deviation of 26.09 minutes. What would happen to the confidence interval if Sam sampled an additional 100 customers to the sample? a. It would probably not change b. It would get wider c. Sample size does not impact the width of the confidence interval d. It would become narrower

d. It would become narrower

Step-by-step explanation:

The width of a normal confidence interval is given by:

In which z is the critical value according to the confidence level, is the standard deviation of the population and n is the size of the sample.

W and n are inverse proportional, that is, as n(the sample size) increases, W(the width of the interval) decreases, that is, the interval becomes narrower..

So the correct answer is:

d. It would become narrower

Have you ever tried to get a running start and slide across a smooth, wooden floor while wearing socks? What happens if you try the same thing on a carpeted floor or while wearing shoes? The amount of friction between your feet and the floor surface determines how well you can slide. Some combinations of surfaces, such as socks on a wooden floor, produce very little friction. Other combinations, such as rubber soles on a wooden floor, produce much more friction. In this project you'll do a much smaller-scale friction experiment by launching tiny objects along a surface with a rubber band. How do you think friction will affect how far the objects slide?

Background

Friction is the force that opposes motion between two surfaces that are touching one another. Friction is a very important part of everyday life—without it, you wouldn't be able to walk because your feet would just slip on the floor! Sometimes it is very important for surfaces to have high friction, such as the rubber tires of a car on the road. Other times we want surfaces to have low friction, such as when you go down a slide at the playground or sled on a snowy hill. The amount of friction changes depending on which materials come into contact with one another.

Step-by-step explanation: