Finding the Fourth Proportional to 1,158.90, 1,599.12 and 661.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,158.90 : 1,599.12 = 661.50 : x
2. Step 2: Convert to fraction form
   1,158.90/1,599.12 = 661.50/x
3. Step 3: Cross multiply
   1,158.90x = 1,599.12 × 661.50
4. Step 4: Simplify right side
   1,158.90x = 1,057,817.88
5. Step 5: Solve for x
   x = 1,057,817.88/1,158.90
6. Step 6: Final answer
   x = 912.78