Finding the Fourth Proportional to 1,141.31, 1,575.25 and 643.95

Step by Step Solution

1. Step 1: Write the proportion equation
   1,141.31 : 1,575.25 = 643.95 : x
2. Step 2: Convert to fraction form
   1,141.31/1,575.25 = 643.95/x
3. Step 3: Cross multiply
   1,141.31x = 1,575.25 × 643.95
4. Step 4: Simplify right side
   1,141.31x = 1,014,380.63
5. Step 5: Solve for x
   x = 1,014,380.63/1,141.31
6. Step 6: Final answer
   x = 888.78