During his 12 minute exercise session, Brain spent 35% of his time doing sit ups. How many seconds of Brain's exercise session were spent doing sit-ups?

Options

A. `4.2`
B. `35`
C. `252`
D. `720`

Answer

To solve the problem, we need to determine how many seconds Brian spent doing sit-ups during his 12-minute exercise session, where he spent 35% of that time on sit-ups.

### Step-by-step Solution:

1. **Convert minutes to seconds**:
- We know that 1 minute is equal to 60 seconds. Therefore, to convert 12 minutes into seconds, we multiply:
\[ 12 \text{ minutes} \times 60 \text{ seconds/minute} = 720 \text{ seconds} \]

2. **Calculate 35% of the total seconds**:
- To find out how many seconds Brian spent doing sit-ups, we need to calculate 35% of 720 seconds. The formula for finding a percentage of a value is:
\[ \text{Percentage} = \left(\frac{\text{Percentage value}}{100}\right) \times \text{Total value} \]
- Here, the percentage value is 35, and the total value is 720 seconds. Thus, we calculate:
\[ 35\% \text{ of } 720 = \left(\frac{35}{100}\right) \times 720 \]

3. **Perform the multiplication**:
- First, multiply 720 by 35:
\[ 720 \times 35 = 25200 \]
- Now, divide by 100 to get the percentage:
\[ \frac{25200}{100} = 252 \text{ seconds} \]

### Final Answer:
Brian spent **252 seconds** doing sit-ups during his exercise session.

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