Finding the Fourth Proportional to 1,561.05, 2,155.04 and 1,206.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,561.05 : 2,155.04 = 1,206.18 : x
2. Step 2: Convert to fraction form
   1,561.05/2,155.04 = 1,206.18/x
3. Step 3: Cross multiply
   1,561.05x = 2,155.04 × 1,206.18
4. Step 4: Simplify right side
   1,561.05x = 2,599,369.16
5. Step 5: Solve for x
   x = 2,599,369.16/1,561.05
6. Step 6: Final answer
   x = 1,665.14