Density and Design Problems Answers

A company needs to package 2,400 pencils. A box in the shape of a rectangular prism can hold 60 pencils. A cylindrical container can hold 80 pencils. Each box costs the company $0.50, while each cylindrical container costs $0.75.Which packaging should the company use to minimize cost? Explain.

The population density of Peru one year was approximately 23 people per square kilometer. Brazil has a land area of approximately 8.5 million square kilometers.If Brazil had the same population density as Peru that year, approximately how many people were living in Brazil?

Marina wants to install security cameras in her store, which has dimensions 48 feet by 48 feet. Each camera can view an area of approximately 128 ft2, with a viewing area shaped like a right triangle. The distance between grid lines is 4 feet.

Crop yield is the ratio of the number of bushels harvested to the number of acres used for the harvest. This year, a large farm harvested rice from 690 acres of farmland. The crop yield was 7,553 bushels per acre.Approximately how many bushels of rice were harvested?

A city’s bus line is used more as the urban population density increases. The more people in an area, the more likely bus lines will be utilized.The population of City A, in Texas, is 29,455 and covers an area of 19.42 mi2. The population of City B, in Alabama, is 34,890 and covers an area of 25.4 mi2.Which city’s residents are more likely to use public buses? Explain.

A scientist has four petri dishes of different sizes. Each dish contains a different number of bacteria.

Orchid wants to retile her bathroom floor, which has an area of 40 square feet. She is deciding between two types of custom tiles. The square tile is foot by foot and costs $0.45 per tile. The rectangular tile is 2 feet by foot and costs $0.80 per tile.Which tile should Orchid choose to minimize costs? Explain.

A shoe store owner is designing the layout of the displays in his store. The floor area for the store is 1,600 square feet. The owner wants to have circular displays for the shoes, each with a radius of 6 feet, and a 48-square-foot rectangular cashier’s station in the corner. Customers should be able to easily walk around the shoe displays, so there must be at least a 4-foot walkway around each. The owner started drawing the layout shown.The distance between grid lines is 4 feet.

The table shows the number of resident geese living in four different ponds.

A medical researcher has two petri dishes containing viruses. Dish B has a population density of 1.2 viruses per square millimeter. Dish A has an area of about 2,826 square millimeters.If both petri dishes have the same population density, approximately how many viruses are in Dish A?