Adevelopmental psychologist interested in how television watching relates to reading ability decides to conduct a study. she records the tv watching and reading habits of a group of toddlers in a community. she examines these habits again when the children enter kindergarten and then once more when they complete first grade. she is using the method.

Longitudinal

Step-by-step explanation:

A longitudinal survey consists of a research that implies several repeated observations of the same variables over certain prefined periods of time, in this case the psychologist is repeating in different times (kindergarten, first grade) and measures the same variables over this period of time (reading habits)

answer: expected value of x = 1.0

step-by-step explanation:

p(x=0) = 0.25

p(x=1) = 0.50

p(x=2) = 0.25

expected value for x = 0×0.25 + 1×0.5 + 2×0.25 = 1.0

answer set (b) 0.5, 3/4 80% is in order from least to greatest.  

step-by-step explanation:

in order to compare rational numbers to each other, it is much easier if they are in the same form.   typically, the best form in which to evaluate rational numbers is in decimals.   in order to convert a percent to a decimal, you would divide the given percentage by 100.   you can also accomplish the conversion by moving the decimal point over two places to the left.   for example, the decimal value of 80% is 80/100, or 0.8.   in order to convert a fraction to a decimal, you need to divide the numerator by the denominator.   for example, 3/4 is 0.75.   so, for choice (b) 0.5 3/4 (0.75), 80% (0.8) is the only choice in which the numbers are in order from least to greatest.