To estimate the mean number of text messages sent by cell-phone users, a researcher chooses a location on a college campus in the city and surveys the first 50 people who walk past. These subjects are asked how many text
messages they have sent in the past 24 hours. Is it likely that bias will be present in the sample?
Because this is a convenience sample, it is likely that the sample results will be unbiased.
Because this is a convenience sample of college students, it is likely that bias is present and that the results will
overestimate the mean number of text messages sent.
Because this is a convenience sample of college students, it is likely that bias is present and that the results will
underestimate the mean number of text messages sent.
Because this is a voluntary response sample of college students, it is likely that bias is present and that the resul
will overestimate the mean number of text messages sent.

answer:  

step-by-step explanation:

here x represents the height of the pole,

and, the height of the shadow of the pole is 12 feet.

also, the angle of elevation from the top of the pole is 40°,

therefore,

by the low of sine,

which is the required equation for finding the value of x,

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places

i dont know the answer but here's a picture of a dog