Finding the Fourth Proportional to 1,290.45, 1,779.75 and 1,091.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,290.45 : 1,779.75 = 1,091.76 : x
2. Step 2: Convert to fraction form
   1,290.45/1,779.75 = 1,091.76/x
3. Step 3: Cross multiply
   1,290.45x = 1,779.75 × 1,091.76
4. Step 4: Simplify right side
   1,290.45x = 1,943,059.86
5. Step 5: Solve for x
   x = 1,943,059.86/1,290.45
6. Step 6: Final answer
   x = 1,505.72