Finding the Fourth Proportional to 1,012.78, 1,399.67 and 764.01

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.78 : 1,399.67 = 764.01 : x
2. Step 2: Convert to fraction form
   1,012.78/1,399.67 = 764.01/x
3. Step 3: Cross multiply
   1,012.78x = 1,399.67 × 764.01
4. Step 4: Simplify right side
   1,012.78x = 1,069,361.88
5. Step 5: Solve for x
   x = 1,069,361.88/1,012.78
6. Step 6: Final answer
   x = 1,055.87