Finding the Fourth Proportional to 1,399.71, 1,931.60 and 770.22

Step by Step Solution

1. Step 1: Write the proportion equation
   1,399.71 : 1,931.60 = 770.22 : x
2. Step 2: Convert to fraction form
   1,399.71/1,931.60 = 770.22/x
3. Step 3: Cross multiply
   1,399.71x = 1,931.60 × 770.22
4. Step 4: Simplify right side
   1,399.71x = 1,487,753.81
5. Step 5: Solve for x
   x = 1,487,753.81/1,399.71
6. Step 6: Final answer
   x = 1,062.90