Finding the Fourth Proportional to 1,390.48, 1,918.68 and 769.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.48 : 1,918.68 = 769.48 : x
2. Step 2: Convert to fraction form
   1,390.48/1,918.68 = 769.48/x
3. Step 3: Cross multiply
   1,390.48x = 1,918.68 × 769.48
4. Step 4: Simplify right side
   1,390.48x = 1,476,385.89
5. Step 5: Solve for x
   x = 1,476,385.89/1,390.48
6. Step 6: Final answer
   x = 1,061.78