At a community garden, each of 120 volunteers worked either a morning shift or an afternoon shift and planted either herbs or vegetables. The table shows the results.
| Shift | Herbs | Vegetables | Total |
|---|---|---|---|
| Morning | 28 | 42 | 70 |
| Afternoon | 20 | 30 | 50 |
| Total | 48 | 72 | 120 |
A volunteer is selected at random from the volunteers who planted herbs. What is the probability that the selected volunteer worked the morning shift?