Why is scarcity an important concept in economics

Mr. mann's science students were experimenting with speed. they set up a 1 meter (100 cm) track. the students used balls instead of cars. the balls were different sizes and made of different materials. four at a time, students rolled balls around the track to see which had the fastest and slowest speeds. some of their data are shown in the table. which ball will take the longest to complete one lap around the track?

Janette goes into an electronics superstore to buy a new computer. the salesperson works with her to find the right model, and she agrees to buy a new computer for $500 and a floor-model 18-inch monitor for $100. just when she is ready to pay, the salesperson walks away for a minute and then comes back to inform her that the monitor she was ready to purchase can't be sold for < $125. she agrees to the extra $25 even though they had initially agreed on the $100 selling price. janette has fallen for the technique of gaining compliance.

Dominic and stacy each have a stamp collection. dominic has six fewer stamps than three times the number of stamps stacy has. dominic and stacy decide to give all of their stamps to their younger sister, mary. if stacy had s stamps, which expression represents the number of stamps that mary received? a. (3s − 18)(3s − 6) b. 2s − 18 c. 4s − 6 d. 4s − 18