Question

A family goes grocery shopping every week. in a month the costs of the groceries are $72.42, $91.50, $58.99, and $69.02. 5. what is the mean? 6. what is the standard devi

Answer 1

1) Mean
The mean is given by the sum of the data divided by the number of data (4, in this case):

`\mu = (1)/(N) \sum x_i = (1)/(4)(72.42+91.50+58.99+69.02) = (291.93)/(4)=72.98 $`

2) Standard deviation
The standard deviation is given by:

`\sigma = \sqrt{ (1)/(N) \sum (x_i-\mu)^2 }`
where
`\mu` is the mean, that we already found at point 1), and N=4. Substituting data, we have:

`\sigma = \sqrt{ (1)/(4) ((-0.56)^2+(18.52)^2+(-13.99)^2+(-3.96)^2) } =`

`= \sqrt{ (1)/(4) (554.71)} = √(138.68) =11.78 $`