Final answer:
After buying, dropping off, and adding potatoes, the total weight is calculated to be 15.2 kg with 0.1 kg as the least precise measurement. The result is expressed with two significant figures due to the precision of the bathroom scale used for the final addition of potatoes.
Step-by-step explanation:
The student's question involves determining the mass of potatoes in bags by performing simple addition and subtraction, and then expressing the final result with the correct number of significant figures. First, we start with the initial mass of potatoes bought from a grocery store, weighed with a precision of 0.01 kg. Next, we subtract the mass of potatoes that were left at the laboratory, measured with a precision of 0.001 kg. Finally, we add the mass of potatoes measured at home using a bathroom scale with a precision of 0.1 kg. We must remember that in addition and subtraction the final answer can have no more decimal places than the least precise measurement. Therefore, after the mathematical operations, the weight of the potatoes is:
7.56 kg (initial amount) - 6.052 kg (dropped off) + 13.7 kg (added at home) = 15.208 kg
Since the least precise measurement has a precision of 0.1 kg, our final result should also be rounded to the tenth of a kilogram, giving us 15.2 kg. Moreover, the final number of significant figures will match the least precise measurement, which is two significant figures. So the correct and final result is 15.2 kg of potatoes, with two significant figures.