Finding the Fourth Proportional to 1,111.88, 1,533.90 and 645.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.88 : 1,533.90 = 645.88 : x
2. Step 2: Convert to fraction form
   1,111.88/1,533.90 = 645.88/x
3. Step 3: Cross multiply
   1,111.88x = 1,533.90 × 645.88
4. Step 4: Simplify right side
   1,111.88x = 990,715.33
5. Step 5: Solve for x
   x = 990,715.33/1,111.88
6. Step 6: Final answer
   x = 891.03