Finding the Fourth Proportional to 3,931.76, 5,390.67 and 3,861.56

Step by Step Solution

1. Step 1: Write the proportion equation
   3,931.76 : 5,390.67 = 3,861.56 : x
2. Step 2: Convert to fraction form
   3,931.76/5,390.67 = 3,861.56/x
3. Step 3: Cross multiply
   3,931.76x = 5,390.67 × 3,861.56
4. Step 4: Simplify right side
   3,931.76x = 20,816,376.34
5. Step 5: Solve for x
   x = 20,816,376.34/3,931.76
6. Step 6: Final answer
   x = 5,294.42