Finding the Fourth Proportional to 13,390.32, 18,478.45 and 7,421.86

Step by Step Solution

1. Step 1: Write the proportion equation
   13,390.32 : 18,478.45 = 7,421.86 : x
2. Step 2: Convert to fraction form
   13,390.32/18,478.45 = 7,421.86/x
3. Step 3: Cross multiply
   13,390.32x = 18,478.45 × 7,421.86
4. Step 4: Simplify right side
   13,390.32x = 137,144,376.52
5. Step 5: Solve for x
   x = 137,144,376.52/13,390.32
6. Step 6: Final answer
   x = 10,242.06