Final answer:
The most accurate estimate for how many more pounds of green apples were bought is closer to 0 pounds. Calculating the percent uncertainty of the apple bag's weight involves dividing the uncertainty by the average weight and multiplying by 100%. A lighter bag with the same uncertainty has a higher percent uncertainty.
Step-by-step explanation:
The student has asked about the estimation of the difference in pounds between two quantities of apples: 7/8 pound of red apples and 15/16 pound of green apples. To estimate how many more pounds of green apples Carrie buys than pounds of red apples, we can subtract 7/8 from 15/16. Since these fractions are close in value, but not equal, the differences between them would be less than 1/2. Therefore, the most accurate estimate for the difference would be closer to 0 pounds than to any other option provided.
As for the additional information on calculating percent uncertainty, if the average weight of the 5-lb bag of apples is 5.1 pounds with a percent uncertainty of ± 0.3 lb, that would be a 6% uncertainty since 0.3 lb divided by 5.1 lb equals 0.0588, which, when multiplied by 100%, gives approximately 6%.
If the bag were half as heavy, say 2.5 pounds, but the uncertainty in weight remained the same (0.3 lb), the percent uncertainty would become 0.3 lb divided by 2.5 lb, which equals 0.12 or 12% when multiplied by 100%. This shows that for a lighter bag, the absolute uncertainty remains the same but the percent uncertainty increases.