Finding the Fourth Proportional to 1,061.21, 1,590.67 and 402.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,061.21 : 1,590.67 = 402.78 : x
2. Step 2: Convert to fraction form
   1,061.21/1,590.67 = 402.78/x
3. Step 3: Cross multiply
   1,061.21x = 1,590.67 × 402.78
4. Step 4: Simplify right side
   1,061.21x = 640,690.06
5. Step 5: Solve for x
   x = 640,690.06/1,061.21
6. Step 6: Final answer
   x = 603.74