Finding the Fourth Proportional to 1,380.42, 1,905.93 and 989.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.42 : 1,905.93 = 989.46 : x
2. Step 2: Convert to fraction form
   1,380.42/1,905.93 = 989.46/x
3. Step 3: Cross multiply
   1,380.42x = 1,905.93 × 989.46
4. Step 4: Simplify right side
   1,380.42x = 1,885,841.50
5. Step 5: Solve for x
   x = 1,885,841.50/1,380.42
6. Step 6: Final answer
   x = 1,366.14