Finding the Fourth Proportional to 1,387.45, 1,914.69 and 890.29

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.45 : 1,914.69 = 890.29 : x
2. Step 2: Convert to fraction form
   1,387.45/1,914.69 = 890.29/x
3. Step 3: Cross multiply
   1,387.45x = 1,914.69 × 890.29
4. Step 4: Simplify right side
   1,387.45x = 1,704,630.08
5. Step 5: Solve for x
   x = 1,704,630.08/1,387.45
6. Step 6: Final answer
   x = 1,228.60