Finding the Fourth Proportional to 1,291.18, 1,936.59 and 521.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,291.18 : 1,936.59 = 521.50 : x
2. Step 2: Convert to fraction form
   1,291.18/1,936.59 = 521.50/x
3. Step 3: Cross multiply
   1,291.18x = 1,936.59 × 521.50
4. Step 4: Simplify right side
   1,291.18x = 1,009,931.69
5. Step 5: Solve for x
   x = 1,009,931.69/1,291.18
6. Step 6: Final answer
   x = 782.18