Finding the Fourth Proportional to 1,012.23, 1,397.45 and 639.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.23 : 1,397.45 = 639.52 : x
2. Step 2: Convert to fraction form
   1,012.23/1,397.45 = 639.52/x
3. Step 3: Cross multiply
   1,012.23x = 1,397.45 × 639.52
4. Step 4: Simplify right side
   1,012.23x = 893,695.33
5. Step 5: Solve for x
   x = 893,695.33/1,012.23
6. Step 6: Final answer
   x = 882.90