Finding the Fourth Proportional to 1,568.79, 2,165.12 and 870.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,568.79 : 2,165.12 = 870.21 : x
2. Step 2: Convert to fraction form
   1,568.79/2,165.12 = 870.21/x
3. Step 3: Cross multiply
   1,568.79x = 2,165.12 × 870.21
4. Step 4: Simplify right side
   1,568.79x = 1,884,104.72
5. Step 5: Solve for x
   x = 1,884,104.72/1,568.79
6. Step 6: Final answer
   x = 1,200.99