The two variables that we should use are:
- x = number of minutes that the call lasted.
- y = cost of that call.
<h3>
What variables should we use?</h3>
Here we want to study a relation between the cost per call as the function of the minutes that the call lasted.
So, we need to use two variables, x will be the number of minutes that call lasted, this is the independent variable.
And the variable that depends on that should be the cost of the call, let's say, y is the cost of the call.
These are the two variables that we need to model the situation:
y = f(x)
There says:
<em>"The cost of the call is a </em><em>function </em><em>of the number of minutes that the call lasted".</em>
<em />
If you want to learn more about functions, you can read:
<em>brainly.com/question/4025726</em>
Hope this helps you out
answer 68
Answer:
μ ≈ 2.33
σ ≈ 1.25
Step-by-step explanation:
Each person has equal probability of ⅓.
![\left[\begin{array}{cc}X&P(X)\\1&\frac{1}{3}\\2&\frac{1}{3}\\4&\frac{1}{3}\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bcc%7DX%26P%28X%29%5C%5C1%26%5Cfrac%7B1%7D%7B3%7D%5C%5C2%26%5Cfrac%7B1%7D%7B3%7D%5C%5C4%26%5Cfrac%7B1%7D%7B3%7D%5Cend%7Barray%7D%5Cright%5D)
The mean is the expected value:
μ = E(X) = ∑ X P(X)
μ = (1) (⅓) + (2) (⅓) + (4) (⅓)
μ = ⁷/₃
The standard deviation is:
σ² = ∑ (X−μ)² P(X)
σ² = (1 − ⁷/₃)² (⅓) + (2 − ⁷/₃)² (⅓) + (4 − ⁷/₃)² (⅓)
σ² = ¹⁴/₉
σ ≈ 1.25
Answer:
1.1x10^24
Step-by-step explanation:
