Finding the Fourth Proportional to 1,288.90, 1,777.98 and 764.56

Step by Step Solution

1. Step 1: Write the proportion equation
   1,288.90 : 1,777.98 = 764.56 : x
2. Step 2: Convert to fraction form
   1,288.90/1,777.98 = 764.56/x
3. Step 3: Cross multiply
   1,288.90x = 1,777.98 × 764.56
4. Step 4: Simplify right side
   1,288.90x = 1,359,372.39
5. Step 5: Solve for x
   x = 1,359,372.39/1,288.90
6. Step 6: Final answer
   x = 1,054.68