Finding the Fourth Proportional to 1,386.21, 2,077.83 and 691.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.21 : 2,077.83 = 691.50 : x
2. Step 2: Convert to fraction form
   1,386.21/2,077.83 = 691.50/x
3. Step 3: Cross multiply
   1,386.21x = 2,077.83 × 691.50
4. Step 4: Simplify right side
   1,386.21x = 1,436,825.29
5. Step 5: Solve for x
   x = 1,436,825.29/1,386.21
6. Step 6: Final answer
   x = 1,036.52