Finding the Fourth Proportional to 1,392.72, 1,921.95 and 771.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,392.72 : 1,921.95 = 771.72 : x
2. Step 2: Convert to fraction form
   1,392.72/1,921.95 = 771.72/x
3. Step 3: Cross multiply
   1,392.72x = 1,921.95 × 771.72
4. Step 4: Simplify right side
   1,392.72x = 1,483,207.25
5. Step 5: Solve for x
   x = 1,483,207.25/1,392.72
6. Step 6: Final answer
   x = 1,064.97