Finding the Fourth Proportional to 1,442.21, 1,990.05 and 812.63

Step by Step Solution

1. Step 1: Write the proportion equation
   1,442.21 : 1,990.05 = 812.63 : x
2. Step 2: Convert to fraction form
   1,442.21/1,990.05 = 812.63/x
3. Step 3: Cross multiply
   1,442.21x = 1,990.05 × 812.63
4. Step 4: Simplify right side
   1,442.21x = 1,617,174.33
5. Step 5: Solve for x
   x = 1,617,174.33/1,442.21
6. Step 6: Final answer
   x = 1,121.32