Finding the Fourth Proportional to 1,370.45, 1,891.24 and 780.99

Step by Step Solution

1. Step 1: Write the proportion equation
   1,370.45 : 1,891.24 = 780.99 : x
2. Step 2: Convert to fraction form
   1,370.45/1,891.24 = 780.99/x
3. Step 3: Cross multiply
   1,370.45x = 1,891.24 × 780.99
4. Step 4: Simplify right side
   1,370.45x = 1,477,039.53
5. Step 5: Solve for x
   x = 1,477,039.53/1,370.45
6. Step 6: Final answer
   x = 1,077.78