Finding the Fourth Proportional to 1,289.45, 1,779.45 and 699.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,289.45 : 1,779.45 = 699.99 : x
2. Step 2: Convert to fraction form
   1,289.45/1,779.45 = 699.99/x
3. Step 3: Cross multiply
   1,289.45x = 1,779.45 × 699.99
4. Step 4: Simplify right side
   1,289.45x = 1,245,601.85
5. Step 5: Solve for x
   x = 1,245,601.85/1,289.45
6. Step 6: Final answer
   x = 965.99