Finding the Fourth Proportional to 111,205.50, 166,389.72 and 77,990.40

Step by Step Solution

1. Step 1: Write the proportion equation
   111,205.50 : 166,389.72 = 77,990.40 : x
2. Step 2: Convert to fraction form
   111,205.50/166,389.72 = 77,990.40/x
3. Step 3: Cross multiply
   111,205.50x = 166,389.72 × 77,990.40
4. Step 4: Simplify right side
   111,205.50x = 12,976,800,818.69
5. Step 5: Solve for x
   x = 12,976,800,818.69/111,205.50
6. Step 6: Final answer
   x = 116,692.08