Finding the Fourth Proportional to 21,363.12, 29,486.16 and 12,978

Step by Step Solution

1. Step 1: Write the proportion equation
   21,363.12 : 29,486.16 = 12,978 : x
2. Step 2: Convert to fraction form
   21,363.12/29,486.16 = 12,978/x
3. Step 3: Cross multiply
   21,363.12x = 29,486.16 × 12,978
4. Step 4: Simplify right side
   21,363.12x = 382,671,384.48
5. Step 5: Solve for x
   x = 382,671,384.48/21,363.12
6. Step 6: Final answer
   x = 17,912.71