Question

calculating variance. mateo is calculating the variance of his expenses for the week using a spreadsheet. he has calculated the mean using the formula \=average(b2:b13)\, and then found the squared differences of each data point and the mean. then he added up the squared differences using the formula \=sum(d2:d13)\. what is the last step for him to find the variance? he needs to subtract the mean from the sum using the formula \=d13 - b10\. he needs to divide the sum by 7 using the formula \=d13/7\. he needs to add the mean to the sum using the formula \=d13 + b10\. he needs to multiply the sum by 7 using the formula \=d13*7\.

Explanation:

Step1: Recall variance formula

The variance of a sample is the sum of squared - differences from the mean divided by \(n - 1\) (for sample variance), and for a population, it is the sum of squared - differences from the mean divided by \(n\). Here, assuming we are dealing with a population (since no indication of sample), after finding the sum of the squared differences from the mean, we divide the sum by the number of data points.

Step2: Identify number of data points

There are 7 days in a week, so \(n = 7\). After adding up the squared differences (sum in cell D11), to find the variance, we divide this sum by 7.

Answer:

He needs to divide the sum by 7 using the formula "=D11/7"