Customers arrive at the movie theater at the movie time indicated only to find they need to sit through commercials and previews. Many complain that this time is too long. WSJ 2012
determined in a preliminary sample that the standard deviation of the amount of time devoted to
previews is 4 minutes. If we want to estimate the population mean time for previews at movie
theatres with a margin of error of 75 seconds, what sample size should be drawn?
b. Assume a 99% confidence level

answer: t=3

step-by-step explanation:

answer: plz give a pic and answer choices so i can answer!

step-by-step explanation:

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."