Finding the Fourth Proportional to 1,222.98, 1,687.71 and 663.45

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.98 : 1,687.71 = 663.45 : x
2. Step 2: Convert to fraction form
   1,222.98/1,687.71 = 663.45/x
3. Step 3: Cross multiply
   1,222.98x = 1,687.71 × 663.45
4. Step 4: Simplify right side
   1,222.98x = 1,119,711.20
5. Step 5: Solve for x
   x = 1,119,711.20/1,222.98
6. Step 6: Final answer
   x = 915.56