Finding the Fourth Proportional to 1,018.99, 1,535.56 and 921.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,018.99 : 1,535.56 = 921.55 : x
2. Step 2: Convert to fraction form
   1,018.99/1,535.56 = 921.55/x
3. Step 3: Cross multiply
   1,018.99x = 1,535.56 × 921.55
4. Step 4: Simplify right side
   1,018.99x = 1,415,095.32
5. Step 5: Solve for x
   x = 1,415,095.32/1,018.99
6. Step 6: Final answer
   x = 1,388.72