Finding the Fourth Proportional to 1,686.05, 2,326.56 and 978.11

Step by Step Solution

1. Step 1: Write the proportion equation
   1,686.05 : 2,326.56 = 978.11 : x
2. Step 2: Convert to fraction form
   1,686.05/2,326.56 = 978.11/x
3. Step 3: Cross multiply
   1,686.05x = 2,326.56 × 978.11
4. Step 4: Simplify right side
   1,686.05x = 2,275,619.97
5. Step 5: Solve for x
   x = 2,275,619.97/1,686.05
6. Step 6: Final answer
   x = 1,349.68