Finding the Fourth Proportional to 1,287.89, 1,777.28 and 698.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.89 : 1,777.28 = 698.43 : x
2. Step 2: Convert to fraction form
   1,287.89/1,777.28 = 698.43/x
3. Step 3: Cross multiply
   1,287.89x = 1,777.28 × 698.43
4. Step 4: Simplify right side
   1,287.89x = 1,241,300.75
5. Step 5: Solve for x
   x = 1,241,300.75/1,287.89
6. Step 6: Final answer
   x = 963.83