Finding the Fourth Proportional to 1,385.72, 1,912.38 and 764.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,385.72 : 1,912.38 = 764.72 : x
2. Step 2: Convert to fraction form
   1,385.72/1,912.38 = 764.72/x
3. Step 3: Cross multiply
   1,385.72x = 1,912.38 × 764.72
4. Step 4: Simplify right side
   1,385.72x = 1,462,435.23
5. Step 5: Solve for x
   x = 1,462,435.23/1,385.72
6. Step 6: Final answer
   x = 1,055.36