Julia went to Cancun during summer vaction. She recorded the number of pesos she spent on the first five days of her trip in the table below. How many pesos did she spend on the sixth day to make the mean expenditure per day (for six days) 220?
`{:("July",1,2,3,4,5,6),("Pesos spent",250,100,150,100,140,?):}`

Options

A. 120
B. 200
C. 220
D. 320

Answer

To find out how many pesos Julia spent on the sixth day to make the mean expenditure per day for six days equal to 220, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the known values**:
The pesos spent on the first five days are:
- Day 1: 250
- Day 2: 100
- Day 3: 150
- Day 4: 100
- Day 5: 400

2. **Calculate the total pesos spent on the first five days**:
\[ \text{Total for first five days} = 250 + 100 + 150 + 100 + 400 \]
\[ = 1000 \text{ pesos} \]

3. **Set up the equation for the mean**:
Let \( x \) be the amount spent on the sixth day. The mean expenditure for six days is given by:
\[ \text{Mean} = \frac{\text{Total expenditure}}{\text{Number of days}} = \frac{1000 + x}{6} \]
We want this mean to equal 220:
\[ \frac{1000 + x}{6} = 220 \]

4. **Multiply both sides by 6 to eliminate the fraction**:
\[ 1000 + x = 220 \times 6 \]
\[ 1000 + x = 1320 \]

5. **Solve for \( x \)**:
Subtract 1000 from both sides:
\[ x = 1320 - 1000 \]
\[ x = 320 \]

### Conclusion:
Julia spent **320 pesos** on the sixth day.