Finding the Fourth Proportional to 1,389.82, 2,084.72 and 415.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.82 : 2,084.72 = 415.88 : x
2. Step 2: Convert to fraction form
   1,389.82/2,084.72 = 415.88/x
3. Step 3: Cross multiply
   1,389.82x = 2,084.72 × 415.88
4. Step 4: Simplify right side
   1,389.82x = 866,991.27
5. Step 5: Solve for x
   x = 866,991.27/1,389.82
6. Step 6: Final answer
   x = 623.82