Finding the Fourth Proportional to 1,379.50, 1,903.20 and 819.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.50 : 1,903.20 = 819.99 : x
2. Step 2: Convert to fraction form
   1,379.50/1,903.20 = 819.99/x
3. Step 3: Cross multiply
   1,379.50x = 1,903.20 × 819.99
4. Step 4: Simplify right side
   1,379.50x = 1,560,601.89
5. Step 5: Solve for x
   x = 1,560,601.89/1,379.50
6. Step 6: Final answer
   x = 1,131.28