Finding the Fourth Proportional to 1,391.58, 1,910.15 and 1,230.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.58 : 1,910.15 = 1,230.69 : x
2. Step 2: Convert to fraction form
   1,391.58/1,910.15 = 1,230.69/x
3. Step 3: Cross multiply
   1,391.58x = 1,910.15 × 1,230.69
4. Step 4: Simplify right side
   1,391.58x = 2,350,802.50
5. Step 5: Solve for x
   x = 2,350,802.50/1,391.58
6. Step 6: Final answer
   x = 1,689.30