Finding the Fourth Proportional to 1,215.48, 1,821.69 and 521.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,215.48 : 1,821.69 = 521.34 : x
2. Step 2: Convert to fraction form
   1,215.48/1,821.69 = 521.34/x
3. Step 3: Cross multiply
   1,215.48x = 1,821.69 × 521.34
4. Step 4: Simplify right side
   1,215.48x = 949,719.86
5. Step 5: Solve for x
   x = 949,719.86/1,215.48
6. Step 6: Final answer
   x = 781.35