Chapter 14, Problem 65E

Read the examples of informal surveys given in Exercise 64. Give three new examples of your own. Make them as different as possible from the ones given in Exercise 64 [changing coffee to soup in (ii) is not a new example].

Informal surveys. In everyday life we are constantly involved in activities that can be described as informal surveys, often without even realizing it. Here are some examples.

i. Al gets up in the morning and wants to know what kind of day it is going to be, so he peeks out the window. He doesn't see any dark clouds, so he figures it's not going to rain.

ii. Betty takes a sip from a cup of coffee and burns her lips. She concludes that the coffee is too hot and decides to add a tad of cold water to it.

iii. Carla got her first Math 101 exam back with a C grade on it. The students sitting on each side of her also received C grades. She concludes that the entire Math 101 class received a C on the first exam.

For each of the preceding examples,

a. describe the population.

b. discuss whether the sample is random or not.

c. discuss the validity of the conclusions drawn. (There is no right or wrong answer to this question, but you should be able to make a reasonable case for your position.)