Finding the Fourth Proportional to 1,390.86, 1,919.46 and 769.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.86 : 1,919.46 = 769.86 : x
2. Step 2: Convert to fraction form
   1,390.86/1,919.46 = 769.86/x
3. Step 3: Cross multiply
   1,390.86x = 1,919.46 × 769.86
4. Step 4: Simplify right side
   1,390.86x = 1,477,715.48
5. Step 5: Solve for x
   x = 1,477,715.48/1,390.86
6. Step 6: Final answer
   x = 1,062.45