Finding the Fourth Proportional to 1,561.57, 2,154.98 and 853.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,561.57 : 2,154.98 = 853.40 : x
2. Step 2: Convert to fraction form
   1,561.57/2,154.98 = 853.40/x
3. Step 3: Cross multiply
   1,561.57x = 2,154.98 × 853.40
4. Step 4: Simplify right side
   1,561.57x = 1,839,059.93
5. Step 5: Solve for x
   x = 1,839,059.93/1,561.57
6. Step 6: Final answer
   x = 1,177.70