Finding the Fourth Proportional to 12,978, 17,909.64 and 7,389

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978 : 17,909.64 = 7,389 : x
2. Step 2: Convert to fraction form
   12,978/17,909.64 = 7,389/x
3. Step 3: Cross multiply
   12,978x = 17,909.64 × 7,389
4. Step 4: Simplify right side
   12,978x = 132,334,329.96
5. Step 5: Solve for x
   x = 132,334,329.96/12,978
6. Step 6: Final answer
   x = 10,196.82