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:
3 goes into 81, 27 times.
A nickel = 5 cents = $0.05
A dime = 10 cents = $0.10
Let the number of nickels be x and the number of dimes be y, then
0.05x + 0.1y = 1.6
5x + 10y = 160 . . . (1)
x = y + 11 . . . (2)
Putting (2) into (1) gives\
5(y + 11) + 10y = 160
5y + 55 + 10y = 160
15y = 160 - 55 = 105
y = 105/15 = 7
x = 7 + 11 = 18
Therefore, He has 18 nickels and 7 dimes.
Answer:
multiplied
Step-by-step explanation: