Finding the Fourth Proportional to 1,222.87, 1,687.56 and 663.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.87 : 1,687.56 = 663.34 : x
2. Step 2: Convert to fraction form
   1,222.87/1,687.56 = 663.34/x
3. Step 3: Cross multiply
   1,222.87x = 1,687.56 × 663.34
4. Step 4: Simplify right side
   1,222.87x = 1,119,426.05
5. Step 5: Solve for x
   x = 1,119,426.05/1,222.87
6. Step 6: Final answer
   x = 915.41