It helps if you have an example, like f(x) = 2x+3
What you typically do, is:
- draw xy axis, label them (ie., 1,2,3,4 along both axes)
- calculate the f(x) values for several x (e.g., -2, 0, 1, 3, doesn't matter).
- plot the calculated values as points. The calculated f(x) is your y value.
- sketch a smooth line through the points. It helps if you know in advance if the line is going to be straight or curved.
- The more points you calculate, the more accurate your graph will be
For a probability distribution the expected value is the summation of product of probabilities with their respective data values. Let x be the probability that Jackson goes gym for 2 days and y be the probability that he goes gym for 3 days.
For the given case we have following values and their probabilities:
0 : 0.1
2 : x
3 : y
So the expected value will be = 0(0.1) + 2(x) + 3(y)
Expected value is given to be 2.05. So we can write the equation as:
2x + 3y = 2.05 (Equation 1)
Also for a probability distribution, the sum of probabilities must always equal to 1. So we can set up the second equation as:
0.1 + x + y = 1
x + y = 0.9 (Equation 2)
From Equation 2 we can write the value of x to be x = 0.9 - y. Using this value in equation 1, we get:
2(0.9 - y) + 3y = 2.05
1.8 - 2y + 3y = 2.05
1.8 + y = 2.05
y = 0.25
Using the value of y in equation 2 we get value of x to be 0.65
Therefore we can conclude that:
The probability that Jackson goes to gym for 2 days is 0.65 and the probability that he goes to gym for 3 days is 0.25
Discrete data is the answer
