Finding the Fourth Proportional to 1,386.58, 1,914.78 and 890.09

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.58 : 1,914.78 = 890.09 : x
2. Step 2: Convert to fraction form
   1,386.58/1,914.78 = 890.09/x
3. Step 3: Cross multiply
   1,386.58x = 1,914.78 × 890.09
4. Step 4: Simplify right side
   1,386.58x = 1,704,326.53
5. Step 5: Solve for x
   x = 1,704,326.53/1,386.58
6. Step 6: Final answer
   x = 1,229.16