Question

four research teams measured the density of a new alloy, and what each team wrote in its team notebook is shown in the table below. suppose a later and more reliable measurement gives 7.10 g/cm³ for the density of the same alloy. decide which of the earlier measurements was the most accurate, and which was the most precise.

team	what was written in the notebook	most accurate measurement	most precise measurement
b	\between 7.30g/cm³ and 7.40g/cm³\
c	\6.60g/cm³\
d	\8.10g/cm³ ± 0.25g/cm³\

Explanation:

Step1: Define accuracy and precision

Accuracy is closeness to true - value, precision is closeness of measurements to each other.

Step2: Analyze accuracy

The true value is $7.10\ g/cm^{3}$.
For team A: The value is $6.1\ g/cm^{3}$, far from $7.10\ g/cm^{3}$.
For team B: The range is from $7.30\ g/cm^{3}$ to $7.40\ g/cm^{3}$, closest to $7.10\ g/cm^{3}$ among all.
For team C: The value is $6.60\ g/cm^{3}$, not close to $7.10\ g/cm^{3}$.
For team D: The value is $8.10\ g/cm^{3}$, far from $7.10\ g/cm^{3}$. So team B is most accurate.

Step3: Analyze precision

Precision is related to the spread of measurements. Team D has a measurement with an uncertainty of $\pm0.25\ g/cm^{3}$, while team A has a percentage - based uncertainty, team B has a range, and team C has a single value with no uncertainty shown. A smaller spread indicates higher precision. Since team C has a single value (no spread in the reported value), team C is most precise.

Answer:

Most accurate measurement: Team B
Most precise measurement: Team C