Finding the Fourth Proportional to 1,388.07, 1,916.45 and 890.93

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.07 : 1,916.45 = 890.93 : x
2. Step 2: Convert to fraction form
   1,388.07/1,916.45 = 890.93/x
3. Step 3: Cross multiply
   1,388.07x = 1,916.45 × 890.93
4. Step 4: Simplify right side
   1,388.07x = 1,707,422.80
5. Step 5: Solve for x
   x = 1,707,422.80/1,388.07
6. Step 6: Final answer
   x = 1,230.07