Finding the Fourth Proportional to 1,386.81, 2,079.50 and 769.59

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.81 : 2,079.50 = 769.59 : x
2. Step 2: Convert to fraction form
   1,386.81/2,079.50 = 769.59/x
3. Step 3: Cross multiply
   1,386.81x = 2,079.50 × 769.59
4. Step 4: Simplify right side
   1,386.81x = 1,600,358.56
5. Step 5: Solve for x
   x = 1,600,358.56/1,386.81
6. Step 6: Final answer
   x = 1,153.99