Finding the Fourth Proportional to 1,111.12, 1,533.54 and 645.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.12 : 1,533.54 = 645.40 : x
2. Step 2: Convert to fraction form
   1,111.12/1,533.54 = 645.40/x
3. Step 3: Cross multiply
   1,111.12x = 1,533.54 × 645.40
4. Step 4: Simplify right side
   1,111.12x = 989,746.72
5. Step 5: Solve for x
   x = 989,746.72/1,111.12
6. Step 6: Final answer
   x = 890.76