[maka09]

can any body help me with these .  i would relly appreciate it to the bone

A laboratory instructor gives a sample of powdered metal to each of four students, A, B, C,and D, and they weigh the samples. The results of their multiple trials follow. The true value is 8.14 g.

A:   8.34 g, 8.32 g, 8.35 g
B:   8.51 g, 8.28 g, 8.05 g
C:   8.19 g, 8.14 g, 8.09 g
D:   8.2 g, 8.24 g, 7.98 g

Use these figures to answer the following questions. (For each question, enter the letter(s) for the correct student(s) in the answer box.)
(a). Calculate the average mass from each set of data. Which set(s) is(are) most accurate?
Precision and accuracy are not the same thing! Make sure you understand what each term means.

(b). Precision is a measure of the average of the deviations of each piece of data from the average value. Which set(s) of data is(are) the most precise?
(c). Which set of data has the best combination of accuracy and precision?
(d). Which set of data has the worst combination of accuracy and precision?

[anon13]

I need help with this as well. Although, my question has different values.
True value: 8.48 g
A:   8.51 g, 8.48 g, 8.45 g
B:   8.15 g, 8.3 g, 8.45 g
C:   8.36 g, 8.54 g, 8.54 g
D:   8.7 g, 8.67 g, 8.69 g
I thought I was doing it right, but it keeps telling me that my answers are wrong.

(a). Calculate the average mass from each set of data. Which set(s) is(are) most accurate?
I found the average of each set, and I got 2 sets (AC) to equal the true value.

(b). Precision is a measure of the average of the deviations of each piece of data from the average value. Which set(s) of data is(are) the most precise?
I took each value in a set and subtarcted the average from it. Then I took those numbers and found the average. I got 2 sets (BC) to equal 0. Then

(c). Which set of data has the best combination of accuracy and precision?
Since I got C for the accuracy and precision questions, it makes sense that C would be the best combinations of accuracy and precision.

(d). Which set of data has the worst combination of accuracy and precision?
Because I didn't get D for any of the answers, it would make sense that it has the worst combination of accuracy and precision.

What am I doing wrong?