Samantha is driving at a constant speed of 55 miles per hour. At this rate,how many miles does he travel in 40 minutes
2 answers:
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Answer:
5
Step-by-step explanation:
The equation is given in slope-intercept form. Slope-intercept form is a way of writing the equation of a line in the format
, such that the coefficient of the parameter (x) is the slope, and constant (b) is the y-intercept. What that essentially means is,
The slope of a line is its rate of change, and the y-intercept is where the graph of the line intersects the y-axis. One can apply this knowledge here by saying that, the equation is given in the slope-intercept form, and the coefficient (
) equals (
), therefore the slope is (
).
Answer:
Now we can calculate the second moment with the following formula:
And replacing we got:
And the variance is given by:
And replacing we got:
And the standard deviation is just the square root of the variance:
Step-by-step explanation:
Previous concepts
For this case we define the random variable X =" how many children the couple will have" and we know the following distribution:
X 1 2 3
P(X) 0.52 0.250 0.230
The expected value of a random variable X is the n-th moment about zero of a probability density function f(x) if X is continuous, or the weighted average for a discrete probability distribution, if X is discrete.
The variance of a random variable X represent the spread of the possible values of the variable. The variance of X is written as Var(X).
Solution to the problem
For this case we can find the expected value with the following formula:
And replacing we got:
Now we can calculate the second moment with the following formula:
And replacing we got:
And the variance is given by:
And replacing we got:
And the standard deviation is just the square root of the variance: