Finding the Fourth Proportional to 1,390.96, 1,919.55 and 801.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.96 : 1,919.55 = 801.55 : x
2. Step 2: Convert to fraction form
   1,390.96/1,919.55 = 801.55/x
3. Step 3: Cross multiply
   1,390.96x = 1,919.55 × 801.55
4. Step 4: Simplify right side
   1,390.96x = 1,538,615.30
5. Step 5: Solve for x
   x = 1,538,615.30/1,390.96
6. Step 6: Final answer
   x = 1,106.15