Finding the Fourth Proportional to 12,912, 19,368.72 and 3,678.72

Step by Step Solution

1. Step 1: Write the proportion equation
   12,912 : 19,368.72 = 3,678.72 : x
2. Step 2: Convert to fraction form
   12,912/19,368.72 = 3,678.72/x
3. Step 3: Cross multiply
   12,912x = 19,368.72 × 3,678.72
4. Step 4: Simplify right side
   12,912x = 71,252,097.64
5. Step 5: Solve for x
   x = 71,252,097.64/12,912
6. Step 6: Final answer
   x = 5,518.29