Answer:
a) The act of selecting a sample of students that are enrolled in statistics classes exclusively is a kind of non-random selection, and <u>may contribute for the selection bias to happen since this sample population isn't representative</u> when related to all the students enrolled in this large university.
b) The non-response bias could happen when, from the 500 students sample, some of them might not be able to answer to the survey sent on their email, or simply chose not to answer it, declining to participate. With <u>less answers, the survey becomes less representative</u>.
c) The response bias could happen if students answer to their surveys in an innacurate way, usually if they support their opinion on personal beliefs that aren't always shared by the rest of the sample population. Since <u>the aim of the survey is to know the students' opinion on the foreign language classes topic, it is expected that response bias happens</u>, having in mind that opinion is a particular thought of each individual.
d) The most serious bias is the selection bias, since the validity of the whole research would be compromised if the sample population isn't representative of the group you aim to study. Without the correct representation of the aim group, the results from the survey are meaningless.
Answer:
The expected revenue of the tour operator is 985.
Step-by-step explanation:
There are two outcomes:
Either less than 21 tourists show up and the operator does not have to pay anything. Or 21 tourists show up and the operator has to repay 100.
Anyways, initially he gets the price of all the tickets sold. That is 21 each at 50, so 
.
Then, we need to find the probability that all of the 21 tourists show up. In this case, we have to subtract 100 from the revenue.
Each tourist has a 0.02 probability of not showing up. This means that each has a 1-0.02 = 0.98 probability of showing up. So the probability P that all 21 tourists show up is 
.
So, the expected revenue of the tour operator is
Rounded up, the expected revenue of the tour operator is 985.
Answer:
$68.97
Step-by-step explanation:
Markup is the difference between the cost of an item and the price at which it is sold:
cost price + markup = selling price
Here, the markup is said to be 70%. The base for that percentage can be either the cost price or the selling price. The way this question is worded suggests the markup is 70% of the cost price.
So, we have ...
cost price + 0.70 × cost price = selling price
or
cost price × (1 + 0.70) = selling price
__
Then, to find the cost price, we can divide by its coefficient in this equation. Doing that gives ...
cost price = (selling price)/1.70
cost price = $117.25/1.70 = $68.97
The store's purchase price before the markup for this item was $68.97.
10 or u could do 25 divided by 2.5 is 10
