Bookstore Inventory Tracking

Back to Trailhead Missions

The Cozy Corner Bookstore is tracking its inventory of a popular novel throughout a busy Saturday. They start the day with 250 copies of the book.

  • From 9 am. to 10 am., they sell 35 copies.
  • From 10 am. to 11 am., they sell 48 copies.
  • From 11 am. to 12 pm., they sell 52 copies.
  • At noon, they receive a new shipment of 150 copies.
  • From 1 pm. to 2 pm., they sell 63 copies.
  • From 2 pm. to 3 pm., they sell 59 copies.
  • At 5 pm., they have 78 copies left in stock.

How many copies of the book did they sell between 3 pm. and 5 pm.?

📚 Cozy Corner Bookstore Saturday Inventory Log 🌅 Start of Day 250 Books 🕤 9:00 am - 10:00 am - 35 Sold 🕙 10:00 am - 11:00 am - 48 Sold 🕚 11:00 am - 12:00 pm - 52 Sold 📦 12:00 pm (Delivery!) + 150 Books 🕐 1:00 pm - 2:00 pm - 63 Sold 🕑 2:00 pm - 3:00 pm - 59 Sold 🕒 3:00 pm - 5:00 pm ❓❓❓ 🕔 5:00 pm (Closing) 78 Left How many copies were sold between 3:00 PM and 5:00 PM?

Solution

Let’s track the inventory throughout the day:

1. Start of day: 250 copies

2. After 10 a.m.: 250 – 35 = 215 copies

3. After 11 a.m.: 215 – 48 = 167 copies

4. After 12 p.m.: 167 – 52 = 115 copies

5. After noon shipment: 115 + 150 = 265 copies

6. After 2 p.m.: 265 – 63 = 202 copies

7. After 3 p.m.: 202 – 59 = 143 copies

We know they have 78 copies at 5 p.m., so to find how many were sold between 3 p.m. and 5 p.m.:

143 – 78 = 65 copies

Therefore, they sold 65 copies of the book between 3 p.m. and 5 p.m.

Solution: Inventory Tracker 🌅 Start of day 250 🕤 After 10 a.m. 250 - 35 = 215 🕙 After 11 a.m. 215 - 48 = 167 🕚 After 12 p.m. 167 - 52 = 115 📦 Noon Shipment! 115 + 150 = 265 🕐 After 2 p.m. 265 - 63 = 202 🕑 After 3 p.m. 202 - 59 = 143 🕵️ How many sold by 5 p.m.? We have 143 books at 3 p.m. We have 78 books at 5 p.m. 143 - 78 = 65 Sold between 3 PM and 5 PM: 65 Copies