Finding the Fourth Proportional to 875.69, 1,309.59 and 778.76

Step by Step Solution

1. Step 1: Write the proportion equation
   875.69 : 1,309.59 = 778.76 : x
2. Step 2: Convert to fraction form
   875.69/1,309.59 = 778.76/x
3. Step 3: Cross multiply
   875.69x = 1,309.59 × 778.76
4. Step 4: Simplify right side
   875.69x = 1,019,856.31
5. Step 5: Solve for x
   x = 1,019,856.31/875.69
6. Step 6: Final answer
   x = 1,164.63