Finding the Fourth Proportional to 1,038.79, 1,433.78 and 645.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,038.79 : 1,433.78 = 645.58 : x
2. Step 2: Convert to fraction form
   1,038.79/1,433.78 = 645.58/x
3. Step 3: Cross multiply
   1,038.79x = 1,433.78 × 645.58
4. Step 4: Simplify right side
   1,038.79x = 925,619.69
5. Step 5: Solve for x
   x = 925,619.69/1,038.79
6. Step 6: Final answer
   x = 891.06