Thirty women were examined in a hospital by a doctor and the number of heart beats per minute were recorded and summarised as follows. Find the mean heart beats per minute for these women, choosing a suitable method.

Explanation

To find the mean heart beats per minute for the thirty women examined, we can use the direct method for calculating the mean. Here’s a step-by-step solution:

### Step 1: Organize the Data
We need to organize the data into frequency intervals and their corresponding frequencies. Let's assume the data is summarized as follows:

| Heart Rate Interval (beats/min) | Frequency (f) |
|----------------------------------|---------------|
| 65 - 68 | 2 |
...