Finding the Fourth Proportional to 1,012.34, 1,396.86 and 639.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.34 : 1,396.86 = 639.52 : x
2. Step 2: Convert to fraction form
   1,012.34/1,396.86 = 639.52/x
3. Step 3: Cross multiply
   1,012.34x = 1,396.86 × 639.52
4. Step 4: Simplify right side
   1,012.34x = 893,319.91
5. Step 5: Solve for x
   x = 893,319.91/1,012.34
6. Step 6: Final answer
   x = 882.43