Finding the Fourth Proportional to 1,222.86, 1,687.67 and 691.86

Step by Step Solution

1. Step 1: Write the proportion equation
   1,222.86 : 1,687.67 = 691.86 : x
2. Step 2: Convert to fraction form
   1,222.86/1,687.67 = 691.86/x
3. Step 3: Cross multiply
   1,222.86x = 1,687.67 × 691.86
4. Step 4: Simplify right side
   1,222.86x = 1,167,631.37
5. Step 5: Solve for x
   x = 1,167,631.37/1,222.86
6. Step 6: Final answer
   x = 954.84