Finding the Fourth Proportional to 1,392.30, 1,921.34 and 771.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.30 : 1,921.34 = 771.30 : x
2. Step 2: Convert to fraction form
   1,392.30/1,921.34 = 771.30/x
3. Step 3: Cross multiply
   1,392.30x = 1,921.34 × 771.30
4. Step 4: Simplify right side
   1,392.30x = 1,481,925.69
5. Step 5: Solve for x
   x = 1,481,925.69/1,392.30
6. Step 6: Final answer
   x = 1,064.37