Finding the Fourth Proportional to 1,093.78, 1,509.59 and 621.89

Step by Step Solution

1. Step 1: Write the proportion equation
   1,093.78 : 1,509.59 = 621.89 : x
2. Step 2: Convert to fraction form
   1,093.78/1,509.59 = 621.89/x
3. Step 3: Cross multiply
   1,093.78x = 1,509.59 × 621.89
4. Step 4: Simplify right side
   1,093.78x = 938,792.93
5. Step 5: Solve for x
   x = 938,792.93/1,093.78
6. Step 6: Final answer
   x = 858.30