Finding the Fourth Proportional to 2,938.56, 4,407.86 and 990.78

Step by Step Solution

1. Step 1: Write the proportion equation
   2,938.56 : 4,407.86 = 990.78 : x
2. Step 2: Convert to fraction form
   2,938.56/4,407.86 = 990.78/x
3. Step 3: Cross multiply
   2,938.56x = 4,407.86 × 990.78
4. Step 4: Simplify right side
   2,938.56x = 4,367,214.58
5. Step 5: Solve for x
   x = 4,367,214.58/2,938.56
6. Step 6: Final answer
   x = 1,486.18