On April 1, the price of gas at Bob’s Corner Station was $3.80 per gallon. On May 1, the price was $4.30 per gallon. On June 1, it was back down to $3.80 per gallon.

To calculate the increases and decreases in the price of gas at Bob’s Corner Station, we can analyze the changes from one date to another.

1. **Between April 1 and May 1:**
- **Price on April 1:** $3.80
- **Price on May 1:** $4.30
- **Increase in price:** $4.30 - $3.80 = $0.50

To find the percentage increase:
\[
\text{Percentage Increase} = \left( \frac{\text{Increase}}{\text{Original Price}} \right) \times 100 = \left( \frac{0.50}{3.80} \right) \times 100 \approx 13.16\%
\]

**Answer:**
- Between April 1 and May 1, Bob’s price increased by **$0.50** (option) or **13.16%** (option).

2. **Between May 1 and June 1:**
- **Price on May 1:** $4.30
- **Price on June 1:** $3.80
- **Decrease in price:** $4.30 - $3.80 = $0.50

To find the percentage decrease:
\[
\text{Percentage Decrease} = \left( \frac{\text{Decrease}}{\text{Original Price}} \right) \times 100 = \left( \frac{0.50}{4.30} \right) \times 100 \approx 11.63\%
\]

**Answer:**
- Between May 1 and June 1, Bob’s price decreased by **$0.50** (option) or **11.63%** (option).

Thus, the final answers are:
1. Between April 1 and May 1: increased by **$0.50** or **13.16%**.
2. Between May 1 and June 1: decreased by **$0.50** or **11.63%**.