Ryan is correct, the mean is about 8.1.
To find the mean, you have to add up all the values, then divide by the total amount.
For Sample A:
60 x 6 + 90 x 7 + 145 x 8 + 150 x 9 + 55 x 10 = 4050
If you add up all the adults, you have 500.
Dividing 4050 by 500 = 8.1
Sample B will produce a very similar result.
Your answer to this is:
0.2
tax reduction: $20.34
amount you're paid minus tax: $657.66
I dont know what you're asking, the property? That is distributive, and the answer of the expression is 7y+35
For the lunch it would be 20$
