Finding the Fourth Proportional to 1,390.99, 1,919.55 and 801.58

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.99 : 1,919.55 = 801.58 : x
2. Step 2: Convert to fraction form
   1,390.99/1,919.55 = 801.58/x
3. Step 3: Cross multiply
   1,390.99x = 1,919.55 × 801.58
4. Step 4: Simplify right side
   1,390.99x = 1,538,672.89
5. Step 5: Solve for x
   x = 1,538,672.89/1,390.99
6. Step 6: Final answer
   x = 1,106.17