Finding the Fourth Proportional to 1,399.66, 1,931.65 and 770.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.66 : 1,931.65 = 770.31 : x
2. Step 2: Convert to fraction form
   1,399.66/1,931.65 = 770.31/x
3. Step 3: Cross multiply
   1,399.66x = 1,931.65 × 770.31
4. Step 4: Simplify right side
   1,399.66x = 1,487,967.39
5. Step 5: Solve for x
   x = 1,487,967.39/1,399.66
6. Step 6: Final answer
   x = 1,063.09