Answer:
See explanation below.
Step-by-step explanation:
The average is measure of central tendency that is also called sample mean and is calculated from the following formula:

This is an estimator of the population mean and is unbiased since the expected value for the estimator is the same parameter as we can see here:

And is important because is the most common measure of central tendency reported on any study.
Is important to remember that this measure can be affected by outliers , for this case when we have outliers is better use the median as a measure of central tendency
18:20
Multiply each side by 2
Answer:
Therefore there are 35 number of 2-point questions and 15 number of 5-point questions.
Step-by-step explanation:
i) let the number of 2 point question is x.
ii) let the number of 5 point questions be y
iii) total number of questions is 50
iv) therefore x + y = 50
v) it is also given that 2x + 5y = 145
vi) solving for the two equations found in iv) and v). Multiplying iv) by 2 we get
2x + 2y = 100
vii) subtracting equation vi) from equation v) we get 3y = 45.
viii) Therefore y = 15.
ix) using the value in viii) and substituting in iv) we get x + 15 = 50.
Therefore x = 50 - 15 = 35
x) Therefore there are 35 number of 2-point questions and 15 number of 5-point questions.
You can tell which animal is faster by pacing