Estimate the population standard deviation of the data shown. Use class midpoints and round your answer to 2 decimal places.
| Class interval | Frequency |
|---|---|
| 10–14 | 5 |
| 15–19 | 9 |
| 20–24 | 6 |
| 25–29 | 4 |
Estimate the standard deviation of the grouped data below. Give your answer to 2 decimal places.
| Score | Frequency |
|---|---|
| 1–5 | 7 |
| 6–10 | 12 |
| 11–15 | 9 |
| 16–20 | 2 |
The ages of attendees at an event are grouped as below. Calculate an estimate of the standard deviation of the ages. Round your answer to 2 decimal places.
| Age (years) | Frequency |
|---|---|
| 30–39 | 4 |
| 40–49 | 9 |
| 50–59 | 12 |
| 60–69 | 7 |
| 70–79 | 3 |
The times (in seconds) to complete a task are grouped as follows. Calculate the standard deviation of the times. Round to 2 decimal places.
| Time () | Frequency |
|---|---|
| 6 | |
| 14 | |
| 22 | |
| 18 | |
| 9 | |
| 5 |
A sample of 30 weights (in kg) is grouped as follows. Calculate the standard deviation of the weights using class midpoints. Give your answer to 2 decimal places.
| Weight (kg) | Frequency |
|---|---|
| 55–64 | 8 |
| 65–74 | 12 |
| 75–84 | 7 |
| 85–94 | 3 |
Find the population standard deviation for the grouped data. Round your answer to 2 decimal places.
| Value | Frequency |
|---|---|
| 20–24 | 2 |
| 25–29 | 7 |
| 30–34 | 10 |
| 35–39 | 1 |
Estimate the population standard deviation of the following grouped data. Round to 2 decimal places.
| Class interval | Frequency |
|---|---|
| 0–4 | 3 |
| 5–9 | 7 |
| 10–14 | 12 |
| 15–19 | 5 |
| 20–24 | 3 |
Statistics
The heights of a group of plants are shown in the following table.
| Height (m) | Frequency |
|---|---|
| 2.5–4.5 | 5 |
| 4.5–6.5 | 11 |
| 6.5–8.5 | 18 |
| 8.5–10.5 | 10 |
| 10.5–12.5 | 6 |
Calculate the standard deviation of the heights using midpoints. Give the answer to 2 decimal places.
[6]A set of reaction times (ms) is grouped as shown. Estimate the sample standard deviation using class midpoints. Round to 2 decimal places.
| Time (ms) | Frequency |
|---|---|
| 200–249 | 3 |
| 250–299 | 8 |
| 300–349 | 12 |
| 350–399 | 9 |
| 400–449 | 3 |
A class’s test scores are grouped in the following table. The estimated mean score is . Find an estimate of the standard deviation. Round to 2 decimal places.
| Score | Frequency |
|---|---|
| 40–49 | 3 |
| 50–59 | |
| 60–69 | 12 |
| 70–79 | 7 |
| 80–89 | 2 |
A factory measures diameters (mm) of parts, grouped as follows. Estimate the population standard deviation. Round to 2 decimal places.
| Diameter (mm) | Frequency |
|---|---|
| 45–54 | 5 |
| 55–64 | 9 |
| 65–74 | 17 |
| 75–84 | 20 |
| 85–94 | 11 |
| 95–104 | 8 |
A company groups delivery sizes (kg) as below. Estimate the sample standard deviation using midpoints. Round your answer to 2 decimal places.
| Mass (kg) | Frequency |
|---|---|
| 0–10 | 8 |
| 10–20 | 14 |
| 20–40 | 10 |
| 40–60 | 6 |
| 60–100 | 2 |
Calculate an estimate for the standard deviation of the following grouped data. Give your answer to 2 decimal places.
| Measurement | Frequency |
|---|---|
| 5–15 | 4 |
| 15–25 | 10 |
| 25–35 | 15 |
| 35–45 | 8 |
| 45–55 | 3 |