Finding the Fourth Proportional to 1,388.16, 1,914.58 and 890.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.16 : 1,914.58 = 890.84 : x
2. Step 2: Convert to fraction form
   1,388.16/1,914.58 = 890.84/x
3. Step 3: Cross multiply
   1,388.16x = 1,914.58 × 890.84
4. Step 4: Simplify right side
   1,388.16x = 1,705,584.45
5. Step 5: Solve for x
   x = 1,705,584.45/1,388.16
6. Step 6: Final answer
   x = 1,228.67