Finding the Fourth Proportional to 2,071.60, 3,106.80 and 685.12

Step by Step Solution

1. Step 1: Write the proportion equation
   2,071.60 : 3,106.80 = 685.12 : x
2. Step 2: Convert to fraction form
   2,071.60/3,106.80 = 685.12/x
3. Step 3: Cross multiply
   2,071.60x = 3,106.80 × 685.12
4. Step 4: Simplify right side
   2,071.60x = 2,128,530.82
5. Step 5: Solve for x
   x = 2,128,530.82/2,071.60
6. Step 6: Final answer
   x = 1,027.48