Finding the Fourth Proportional to 1,488.78, 2,054.01 and 921.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,488.78 : 2,054.01 = 921.78 : x
2. Step 2: Convert to fraction form
   1,488.78/2,054.01 = 921.78/x
3. Step 3: Cross multiply
   1,488.78x = 2,054.01 × 921.78
4. Step 4: Simplify right side
   1,488.78x = 1,893,345.34
5. Step 5: Solve for x
   x = 1,893,345.34/1,488.78
6. Step 6: Final answer
   x = 1,271.74