Finding the Fourth Proportional to 13,778.67, 18,980.82 and 9,990.71

Step by Step Solution

1. Step 1: Write the proportion equation
   13,778.67 : 18,980.82 = 9,990.71 : x
2. Step 2: Convert to fraction form
   13,778.67/18,980.82 = 9,990.71/x
3. Step 3: Cross multiply
   13,778.67x = 18,980.82 × 9,990.71
4. Step 4: Simplify right side
   13,778.67x = 189,631,868.18
5. Step 5: Solve for x
   x = 189,631,868.18/13,778.67
6. Step 6: Final answer
   x = 13,762.71