Finding the Fourth Proportional to 1,420.53, 2,128.37 and 771.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.53 : 2,128.37 = 771.72 : x
2. Step 2: Convert to fraction form
   1,420.53/2,128.37 = 771.72/x
3. Step 3: Cross multiply
   1,420.53x = 2,128.37 × 771.72
4. Step 4: Simplify right side
   1,420.53x = 1,642,501.84
5. Step 5: Solve for x
   x = 1,642,501.84/1,420.53
6. Step 6: Final answer
   x = 1,156.26