Astudy examined the alertness benefits of higher caffeine intake. in the study, the researchers investigated the link between daily caffeine intake and alertness at work (measured on a 6-point scale where 1 equals"not alert" and 6 equals"very alert"). participants for the study were those who used a popular social networking web site. of the respondents, those who had very high or very low intakes were excluded, leaving a sample size of 49 respondents.
do the data represent a population or a sample?

a. the data represent a population since the data are all the units that are the subject of the study
b. the data represent a sample since the data are a subset of units.
c. the data represent a population since the data are a subset of units.
d. the data represent a sample since the data are all the units that are the subject of the study.

B. The data represent a sample since the data are a subset of units.

True, we have a sample and all the elements on this sample are subset for the units of the population.

Step-by-step explanation:

We need to remember that the population represent all the possible elements or individuals of interest and by the other hand the sample is a subset of the population that is used to analyze patterns in the population of interest

Let's analyze one by one the options.

A. The data represent a population since the data are all the units that are the subject of the study

False, we have a sample size n =49 not all the possible elements of the population for this case we don't have a population.

B. The data represent a sample since the data are a subset of units.

True, we have a sample and all the elements on this sample are subset for the units of the population.

C. The data represent a population since the data are a subset of units.

False, by definition the population CAN'T be a subset of the sample size, and that's not the case.

D. The data represent a sample since the data are all the units that are the subject of the study.

False, the data is a sample BUT are not all the units for the study because that only occurs when we have a population.

step-by-step explanation:

to find if any function is an inverse of the other, put the first equation in as x in the next one. then simplify and solve. if at the end you get the statement y = x, then it is an inverse. if you get anything else, it is not.

hello from mrbilldoesmath!

answer:

(7 x + 6 y) (49 x^2 - 42 x y + 36 y^2)

discussion:

the trick is to recognize that 343 = 7^3 and 216 = 6^3 and, in general,

a^3 + b^3 =   (a + b) (a^2 - a b + b^2).

in our case

343x^3+216y^3   =   (7x)^3 + (6y)^3

so take a = 7x and b = 6y in the above equation to get the answer.

you,

mrb