Finding the Fourth Proportional to 1,369.86, 1,890.35 and 810.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,369.86 : 1,890.35 = 810.21 : x
2. Step 2: Convert to fraction form
   1,369.86/1,890.35 = 810.21/x
3. Step 3: Cross multiply
   1,369.86x = 1,890.35 × 810.21
4. Step 4: Simplify right side
   1,369.86x = 1,531,573.05
5. Step 5: Solve for x
   x = 1,531,573.05/1,369.86
6. Step 6: Final answer
   x = 1,118.05