Finding the Fourth Proportional to 1,390.56, 2,086.72 and 568.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.56 : 2,086.72 = 568.80 : x
2. Step 2: Convert to fraction form
   1,390.56/2,086.72 = 568.80/x
3. Step 3: Cross multiply
   1,390.56x = 2,086.72 × 568.80
4. Step 4: Simplify right side
   1,390.56x = 1,186,926.34
5. Step 5: Solve for x
   x = 1,186,926.34/1,390.56
6. Step 6: Final answer
   x = 853.56