Finding the Fourth Proportional to 1,421.72, 1,961.40 and 890.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.72 : 1,961.40 = 890.52 : x
2. Step 2: Convert to fraction form
   1,421.72/1,961.40 = 890.52/x
3. Step 3: Cross multiply
   1,421.72x = 1,961.40 × 890.52
4. Step 4: Simplify right side
   1,421.72x = 1,746,665.93
5. Step 5: Solve for x
   x = 1,746,665.93/1,421.72
6. Step 6: Final answer
   x = 1,228.56