A frog in the well jumps every day 3 ft. up. But it slides down by 2 ft. How many days it will take the frog to come out of the well if the well is 30 ft. deep?

Options

A. 30
B. 28
C. 27
D. 10

Explanation

To solve the problem of how many days it will take for the frog to come out of a 30 ft deep well, we can break it down step by step.

### Step-by-Step Solution:

1. **Understanding Daily Movement**:
- Each day, the frog jumps up 3 feet but then slides back down 2 feet.
- Therefore, the effective gain in height each day is:
\[ \text{Effective gain} = \text{Jump up} - \text{Slide down} = 3 \text{ ft} - 2 \text{ ft} = 1 \text{ ft} \]

2. **Calculate Height After Several Days**:
- For the first 27 days, the frog will make an effective gain of 1 foot per day.
- After 27 days, the total height gained will be:
\[ \text{Height after 27 days} = 27 \text{ ft} \]

3. **Determine Remaining Height**:
- After 27 days, the frog is at 27 feet. The total height of the well is 30 feet.
- The remaining height to climb is:
\[ \text{Remaining height} = 30 \text{ ft} - 27 \text{ ft} = 3 \text{ ft} \]

4. **Final Jump**:
- On the 28th day, the frog jumps up 3 feet. Since it only needs to reach 30 feet, it will successfully climb out of the well.
- Therefore, the frog will not slide back down after reaching the top.

5. **Total Days Taken**:
- The total number of days taken for the frog to come out of the well is:
\[ \text{Total days} = 27 \text{ days} + 1 \text{ day} = 28 \text{ days} \]

### Final Answer:
The frog will take **28 days** to come out of the well.