Finding the Fourth Proportional to 1,287.58, 1,776.86 and 698.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.58 : 1,776.86 = 698.10 : x
2. Step 2: Convert to fraction form
   1,287.58/1,776.86 = 698.10/x
3. Step 3: Cross multiply
   1,287.58x = 1,776.86 × 698.10
4. Step 4: Simplify right side
   1,287.58x = 1,240,422.48
5. Step 5: Solve for x
   x = 1,240,422.48/1,287.58
6. Step 6: Final answer
   x = 963.38