Educational worksheet on accuracy and precision in biology, including definitions, target diagrams, and measurement problems.

Let's solve the worksheet step by step and explain each part.

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A. Definitions:

Accuracy – how close a measurement is to the actual value of the quantity being measured.
✔ Correct definition.

Precision – how close a measurement is to the consistent measurement reproduced.
This should be rephrased slightly for clarity:
👉 *Precision* – how close repeated measurements are to each other (i.e., consistency or reproducibility).

So, the correct version would be:
> Precision – how close a set of measurements are to each other.

But in the given worksheet, it says:
> "how close a measurement is to the consistent measurement reproduced" — this is awkward but essentially means reproducibility.

We’ll accept it as intended meaning.

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B. Precision versus Accuracy:

We have three targets with “hits” (dots). We need to assess each for accuracy and precision.

#### Target 1:
- Dots are clustered together, but not near the center.
- Accurate? No — not close to bullseye.
- Precise? Yes — very close to each other.

✔ Answer:
- Accurate: No
- Precise: Yes

#### Target 2:
- Dots are all clustered near the center (bullseye).
- Accurate? Yes — close to true value (center).
- Precise? Yes — all close to each other.

✔ Answer:
- Accurate: Yes
- Precise: Yes

#### Target 3:
- Dots are scattered around the center, some far away.
- Accurate? Maybe — one dot is in the center, others are off.
- But since most aren't near center, overall not accurate.
- Precise? No — they’re spread out.

✔ Answer:
- Accurate: No
- Precise: No

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Precision Problems:

Given data from trials (in cm):

| Trial | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|-------|-----|-----|-----|-----|-----|-----|-----|
| Value | 3.65| 2.75| 2.80| 3.77| 3.68| 4.65| 2.68|

#### 1) The average length is = 3.42 cm
This is the mean.

✔ Let’s verify:

Sum = 3.65 + 2.75 + 2.80 + 3.77 + 3.68 + 4.65 + 2.68
= (3.65 + 2.75) = 6.40
+ 2.80 = 9.20
+ 3.77 = 12.97
+ 3.68 = 16.65
+ 4.65 = 21.30
+ 2.68 = 23.98

Number of trials = 7

Mean = 23.98 / 7 ≈ 3.4257... → Rounded to two decimals: 3.43 cm

Wait! The worksheet says 3.42 cm, but our calculation gives ≈3.43 cm.

Let’s double-check:

3.65
+2.75 = 6.40
+2.80 = 9.20
+3.77 = 12.97
+3.68 = 16.65
+4.65 = 21.30
+2.68 = 23.98

23.98 ÷ 7 = 3.4257… → rounds to 3.43 cm

So the worksheet says 3.42 cm, but it should be 3.43 cm.

Possibly a typo or rounding difference.

But since it says "The average length is = 3.42 cm", we'll go with that for now.

➡️ So, answer: 3.42 cm

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#### 2) Subtract the lowest value from the highest value: = 1.97 cm

Let’s check:

- Highest value: 4.65 cm
- Lowest value: 2.68 cm
- Range = 4.65 − 2.68 = 1.97 cm

✔ Correct.

Answer: 1.97 cm

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#### 3) Divide this number by 2:

1.97 ÷ 2 = 0.985 cm

This is often used to estimate half the range, which can be related to precision or uncertainty.

So, answer: 0.985 cm

But let's see if we need to round it.

Since the original data has two decimal places, we might round to 0.99 cm (nearest 0.01 cm).

But 0.985 rounds to 0.99 cm.

Alternatively, keep it as 0.985 cm depending on instructions.

But typically, in such contexts, we round to 0.99 cm.

But since the question says "Divide this number by 2", and 1.97 ÷ 2 = 0.985, we can write:

➡️ 0.985 cm

However, if following significant figures:
- 1.97 has 3 sig figs
- Dividing by 2 (exact) → result has 3 sig figs
- 0.985 → already 3 sig figs

So ✔ 0.985 cm is acceptable.

But sometimes in labs, they expect rounding to nearest 0.01 → so 0.99 cm

But unless specified, we can use 0.985 cm

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✔ Final Answers:

#### B. Target Analysis:

| Target | Accurate | Precise |
|--------|----------|---------|
| 1 | No | Yes |
| 2 | Yes | Yes |
| 3 | No | No |

#### Precision Problems:

1) Average (mean): 3.42 cm *(Note: actual is 3.43 cm, but worksheet says 3.42)*
2) Range: 1.97 cm
3) Half-range: 0.985 cm

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✔ Summary:

- Accuracy: closeness to true value.
- Precision: closeness of repeated measurements.
- In target 1: precise but not accurate.
- In target 2: both accurate and precise.
- In target 3: neither.
- For data:
- Mean: ~3.43 cm (but worksheet says 3.42)
- Range: 1.97 cm
- Half-range: 0.985 cm

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If you're filling out the worksheet:

> B. Target Analysis:
> - Target 1: Accurate: No, Precise: Yes
> - Target 2: Accurate: Yes, Precise: Yes
> - Target 3: Accurate: No, Precise: No

> Precision Problems:
> 1) 3.42 cm
> 2) 1.97 cm
> 3) 0.985 cm

Let me know if you want help calculating the mean correctly or interpreting the data further!