Finding the Fourth Proportional to 1,569.28, 2,165.72 and 870.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,569.28 : 2,165.72 = 870.80 : x
2. Step 2: Convert to fraction form
   1,569.28/2,165.72 = 870.80/x
3. Step 3: Cross multiply
   1,569.28x = 2,165.72 × 870.80
4. Step 4: Simplify right side
   1,569.28x = 1,885,908.98
5. Step 5: Solve for x
   x = 1,885,908.98/1,569.28
6. Step 6: Final answer
   x = 1,201.77