Finding the Fourth Proportional to 1,059.57, 1,461.86 and 640.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,059.57 : 1,461.86 = 640.05 : x
2. Step 2: Convert to fraction form
   1,059.57/1,461.86 = 640.05/x
3. Step 3: Cross multiply
   1,059.57x = 1,461.86 × 640.05
4. Step 4: Simplify right side
   1,059.57x = 935,663.49
5. Step 5: Solve for x
   x = 935,663.49/1,059.57
6. Step 6: Final answer
   x = 883.06