Finding the Fourth Proportional to 1,393.76, 1,922.60 and 870.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,393.76 : 1,922.60 = 870.10 : x
2. Step 2: Convert to fraction form
   1,393.76/1,922.60 = 870.10/x
3. Step 3: Cross multiply
   1,393.76x = 1,922.60 × 870.10
4. Step 4: Simplify right side
   1,393.76x = 1,672,851.63
5. Step 5: Solve for x
   x = 1,672,851.63/1,393.76
6. Step 6: Final answer
   x = 1,200.24