Question

Customers at your store select their groceries from shelves and then pay. Sales records and records of restocks for Flaming Roast Coffee (1 lb size) are as follows:
Number of bags Tue Wed Thu Fri Sat Sun Mon

Sales  5  8  2 19 22 15  3

Restock  6 12 12 18 24  0  0

What is the net change in how many bags are on the shelf, from the beginning of Tuesday to the end of Monday?

Answer 1

Answer:

• The net change in how many bags are on the shelf, from the beginning of Tuesday to the end of Monday is -2.

Explanation:

The change in the number of bags any day is the number of bags is equal to the number of bags purchased to restock less the number of bags sold that day.

• Change = bags purchased to restock - bags sold

At the end of Tuesday, the change is:

• Restock:    6

• Sales:        5

• Change:    6 - 5 = 1    (note that this means that the number of bags increases by 1)

At the end of Wednesday, the change is:

• Restock:    12

• Sales:        8

• Change:    12 - 8 = 4    (the number of bags increases by 4)

At the end of Thursday, the change is:

• Restock:    12

• Sales:        2

• Change:    12 - 2 = 10    (the number of bags increases by 10)

At the end of Friday, the change is:

• Restock:    18

• Sales:        19

• Change:    18 - 19 = - 1    (the number of bags decreases by 1).

At the end of Saturday, the change is:

• Restock:    24

• Sales:        22

• Change:    24 - 22 = 2    (the number of bags increases by 2).

At the end of Sunday, the change is:

• Restock:    0

• Sales:        15

• Change:    0 - 15 = - 15    (the number of bags decreases by 15).

At the end of Monday, the change is:

• Restock:    0

• Sales:        3

• Change:    0 - 3 = - 3    (the number of bags decreases by 3).

The net change in how many bags are on the shelf, from the beginning of Tuesday to the end of Monday equals the algebraic sum of every change:

• Net change = 1 + 4 + 10 + (-1) + 2 + (-15) + (-3)

• Using associative property: (1 + 4 + 10 + 2) - (1 + 15 +3)

• Simplifying: 17 - 19 = -2

Conclusion: the net change in how many bags are on the shelf, from the beginning of Tuesday to the end of Monday is -2, meaning that the number of bags, after taking into account all sales and restock, decreases by 2.