Finding the Fourth Proportional to 1,012.02, 1,396.94 and 639.62

Step by Step Solution

1. Step 1: Write the proportion equation
   1,012.02 : 1,396.94 = 639.62 : x
2. Step 2: Convert to fraction form
   1,012.02/1,396.94 = 639.62/x
3. Step 3: Cross multiply
   1,012.02x = 1,396.94 × 639.62
4. Step 4: Simplify right side
   1,012.02x = 893,510.76
5. Step 5: Solve for x
   x = 893,510.76/1,012.02
6. Step 6: Final answer
   x = 882.90