An auditor reviewing the expense reports of 50 sales agents calculated the mean daily expense to be $142.50. However, it was later discovered that one receipt was incorrectly recorded as $78 instead of its actual amount of $128. What is the corrected mean daily expense for the sales agents?

The correct option is $143.50.

Step 1: Understand the given data
Number of sales agents (n) = 50
Initially calculated mean daily expense = $142.50
Incorrect receipt amount recorded = $78
Actual receipt amount = $128

Step 2: Find the difference in the recorded total expense
The difference between the actual receipt amount and the incorrectly recorded amount is:

$\text{Difference}=\$128-\$78=\$50$

This means the total expense was underestimated by $50.

Step 3: Calculate the change in the mean
Since the increase of $50 is distributed across all 50 sales agents, the increase in the mean daily expense is calculated as:

$\text{Increase in Mean}=\frac{\$50}{50}=\$1.00$

Step 4: Calculate the corrected mean
Add the increase in mean to the initially calculated mean daily expense:

$\text{Corrected Mean}=\$142.50+\$1.00=\$143.50$

Alternatively, calculating via total expenses:
Initial Total Expense = 50 × $142.50 = $7125.00
Corrected Total Expense = $7125.00 + $50 = $7175.00
Corrected Mean = $7175.00 / 50 = $143.50

Thus, the corrected mean daily expense for the sales agents is $143.50.