The degree is "4" and the number of terms is "1"
567,890
+567,096
________
1,134,986
7 out of 10 were carrying a backpack...and 3 out of 10 were not
that means 7/10 of the total students had backpacks and 3/10 of the total students did not
7/10 * 700 = 4900/10 = 490 had backpacks <==
3/10 * 700 = 2100/10 = 210 did not
Answer:
The mean of the total repair time is 150 minutes.
The variance of the total repair time is 725 minutes^2.
Step-by-step explanation:
To solve this problem, we have to use the properties of the mean and the variance. Our random variable is the sum of 3 normal variables.
In the case, for the mean, we have that the mean of the sum of 3 normal variables is equal to the sum of the mean of the 3 variables:

For the variance, we apply the property for the sum of independent variables (the correlation between the variables is 0):
