Finding the Fourth Proportional to 1,209.72, 1,670.40 and 985.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.72 : 1,670.40 = 985.69 : x
2. Step 2: Convert to fraction form
   1,209.72/1,670.40 = 985.69/x
3. Step 3: Cross multiply
   1,209.72x = 1,670.40 × 985.69
4. Step 4: Simplify right side
   1,209.72x = 1,646,490.02
5. Step 5: Solve for x
   x = 1,646,490.02/1,209.72
6. Step 6: Final answer
   x = 1,361.05