Finding the Fourth Proportional to 990.78, 1,483.72 and 747.78

Step by Step Solution

1. Step 1: Write the proportion equation
   990.78 : 1,483.72 = 747.78 : x
2. Step 2: Convert to fraction form
   990.78/1,483.72 = 747.78/x
3. Step 3: Cross multiply
   990.78x = 1,483.72 × 747.78
4. Step 4: Simplify right side
   990.78x = 1,109,496.14
5. Step 5: Solve for x
   x = 1,109,496.14/990.78
6. Step 6: Final answer
   x = 1,119.82