Finding the Fourth Proportional to 1,439.72, 1,987.64 and 1,377.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.72 : 1,987.64 = 1,377.80 : x
2. Step 2: Convert to fraction form
   1,439.72/1,987.64 = 1,377.80/x
3. Step 3: Cross multiply
   1,439.72x = 1,987.64 × 1,377.80
4. Step 4: Simplify right side
   1,439.72x = 2,738,570.39
5. Step 5: Solve for x
   x = 2,738,570.39/1,439.72
6. Step 6: Final answer
   x = 1,902.15