Finding the Fourth Proportional to 1,421.40, 1,961.52 and 791.90

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.40 : 1,961.52 = 791.90 : x
2. Step 2: Convert to fraction form
   1,421.40/1,961.52 = 791.90/x
3. Step 3: Cross multiply
   1,421.40x = 1,961.52 × 791.90
4. Step 4: Simplify right side
   1,421.40x = 1,553,317.88
5. Step 5: Solve for x
   x = 1,553,317.88/1,421.40
6. Step 6: Final answer
   x = 1,092.81