Finding the Fourth Proportional to 1,686.72, 2,326.56 and 987.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,686.72 : 2,326.56 = 987.60 : x
2. Step 2: Convert to fraction form
   1,686.72/2,326.56 = 987.60/x
3. Step 3: Cross multiply
   1,686.72x = 2,326.56 × 987.60
4. Step 4: Simplify right side
   1,686.72x = 2,297,710.66
5. Step 5: Solve for x
   x = 2,297,710.66/1,686.72
6. Step 6: Final answer
   x = 1,362.24