Finding the Fourth Proportional to 1,390.61, 1,916.99 and 1,058.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.61 : 1,916.99 = 1,058.45 : x
2. Step 2: Convert to fraction form
   1,390.61/1,916.99 = 1,058.45/x
3. Step 3: Cross multiply
   1,390.61x = 1,916.99 × 1,058.45
4. Step 4: Simplify right side
   1,390.61x = 2,029,042.86
5. Step 5: Solve for x
   x = 2,029,042.86/1,390.61
6. Step 6: Final answer
   x = 1,459.11