Finding the Fourth Proportional to 1,388.38, 2,074.60 and 1,057.48

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.38 : 2,074.60 = 1,057.48 : x
2. Step 2: Convert to fraction form
   1,388.38/2,074.60 = 1,057.48/x
3. Step 3: Cross multiply
   1,388.38x = 2,074.60 × 1,057.48
4. Step 4: Simplify right side
   1,388.38x = 2,193,841.60
5. Step 5: Solve for x
   x = 2,193,841.60/1,388.38
6. Step 6: Final answer
   x = 1,580.15