Final answer:
Sophie's average monthly salary is calculated by summing her earnings over five months and dividing by the number of months. The total earnings are $16,661, and when divided by 5, the average monthly salary is $3,332.20.
Step-by-step explanation:
To calculate Sophie's average monthly salary over the given months, we need to add up all of her monthly earnings and then divide by the number of months.
June: $3,614
July: $2,873
August: $4,464
September: $3,721
October: $1,989
Total earnings = $3,614 + $2,873 + $4,464 + $3,721 + $1,989 = $16,661
Number of months = 5
Average monthly salary = Total earnings / Number of months
Average monthly salary = $16,661 / 5 = $3,332.20
Therefore, the closest value to Sophie's average monthly salary over these five months is $3,332.20.