Finding the Fourth Proportional to 1,245.78, 1,856.72 and 1,191.51

Step by Step Solution

1. Step 1: Write the proportion equation
   1,245.78 : 1,856.72 = 1,191.51 : x
2. Step 2: Convert to fraction form
   1,245.78/1,856.72 = 1,191.51/x
3. Step 3: Cross multiply
   1,245.78x = 1,856.72 × 1,191.51
4. Step 4: Simplify right side
   1,245.78x = 2,212,303.43
5. Step 5: Solve for x
   x = 2,212,303.43/1,245.78
6. Step 6: Final answer
   x = 1,775.84