Finding the Fourth Proportional to 1,663.72, 2,490.78 and 1,279.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,663.72 : 2,490.78 = 1,279.72 : x
2. Step 2: Convert to fraction form
   1,663.72/2,490.78 = 1,279.72/x
3. Step 3: Cross multiply
   1,663.72x = 2,490.78 × 1,279.72
4. Step 4: Simplify right side
   1,663.72x = 3,187,500.98
5. Step 5: Solve for x
   x = 3,187,500.98/1,663.72
6. Step 6: Final answer
   x = 1,915.89