Finding the Fourth Proportional to 2,123.72, 3,187.60 and 890.80

Step by Step Solution

1. Step 1: Write the proportion equation
   2,123.72 : 3,187.60 = 890.80 : x
2. Step 2: Convert to fraction form
   2,123.72/3,187.60 = 890.80/x
3. Step 3: Cross multiply
   2,123.72x = 3,187.60 × 890.80
4. Step 4: Simplify right side
   2,123.72x = 2,839,508.89
5. Step 5: Solve for x
   x = 2,839,508.89/2,123.72
6. Step 6: Final answer
   x = 1,337.05