Finding the Fourth Proportional to 1,215.89, 1,824.37 and 638.63

Step by Step Solution

1. Step 1: Write the proportion equation
   1,215.89 : 1,824.37 = 638.63 : x
2. Step 2: Convert to fraction form
   1,215.89/1,824.37 = 638.63/x
3. Step 3: Cross multiply
   1,215.89x = 1,824.37 × 638.63
4. Step 4: Simplify right side
   1,215.89x = 1,165,097.41
5. Step 5: Solve for x
   x = 1,165,097.41/1,215.89
6. Step 6: Final answer
   x = 958.23