Finding the Fourth Proportional to 1,387.22, 1,914.12 and 890.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,387.22 : 1,914.12 = 890.30 : x
2. Step 2: Convert to fraction form
   1,387.22/1,914.12 = 890.30/x
3. Step 3: Cross multiply
   1,387.22x = 1,914.12 × 890.30
4. Step 4: Simplify right side
   1,387.22x = 1,704,141.04
5. Step 5: Solve for x
   x = 1,704,141.04/1,387.22
6. Step 6: Final answer
   x = 1,228.46