Finding the Fourth Proportional to 1,391.50, 1,920.41 and 770.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,391.50 : 1,920.41 = 770.50 : x
2. Step 2: Convert to fraction form
   1,391.50/1,920.41 = 770.50/x
3. Step 3: Cross multiply
   1,391.50x = 1,920.41 × 770.50
4. Step 4: Simplify right side
   1,391.50x = 1,479,675.91
5. Step 5: Solve for x
   x = 1,479,675.91/1,391.50
6. Step 6: Final answer
   x = 1,063.37