The management of a large airline wants to estimate the average time after takeoff taken before the crew begins serving snacks a
nd beverages on their flights. Assuming that management has easy access to all of the information that would be required to select flights by each proposed method, which of the following would be reasonable methods of stratified sampling? a. For each day of the week, randomly select 5% of all flights that depart on that day of the week.
b. Divide all flights into the following 4 groups on the basis of scheduled departure time: before 9:00 am 9:00 am to 1:00 pm. 1:00 pm to 5:00 pm, and after 5:00 pm. Randomly select 5% of the flights in each group.
c. For each crew member the airline employs, randomly select 5 flights that the crew member works.
d. Divide the airports from which the airline's fights depart into 4 regions: Northeast, Northwest Southwest and Southeast. Randomly select 5% of all flights departing from airports in each region
In the given question it is used to stratifying the sampling if the population of this scenario it flights takes off when it is divided via some strata.
In option a, In this case, it stratified the sampling, as the population of planes taking off has been divided into the days of the week.
In option b, It also used as the case of stratified sampling.
In options c, it is systematic sampling, that's why it is wrong.
In option d, It is an example of stratifying the sampling.
Because this triangle and trapezoid are reflections of each other when split in half, remove the highlighted parts to make them a rectangle. When made into a rectangle, you can use the formula length * width to find the area of either shape (trapezoid or triangle).
Note you won't be able to do this when solving for the area of ALL trapezoids and triangles.
