Finding the Fourth Proportional to 1,080.74, 1,618.38 and 990.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,080.74 : 1,618.38 = 990.50 : x
2. Step 2: Convert to fraction form
   1,080.74/1,618.38 = 990.50/x
3. Step 3: Cross multiply
   1,080.74x = 1,618.38 × 990.50
4. Step 4: Simplify right side
   1,080.74x = 1,602,997.30
5. Step 5: Solve for x
   x = 1,602,997.30/1,080.74
6. Step 6: Final answer
   x = 1,483.24