Finding the Fourth Proportional to 1,077.69, 1,615.55 and 420.00

Step by Step Solution

1. Step 1: Write the proportion equation
   1,077.69 : 1,615.55 = 420.00 : x
2. Step 2: Convert to fraction form
   1,077.69/1,615.55 = 420.00/x
3. Step 3: Cross multiply
   1,077.69x = 1,615.55 × 420.00
4. Step 4: Simplify right side
   1,077.69x = 678,531.93
5. Step 5: Solve for x
   x = 678,531.93/1,077.69
6. Step 6: Final answer
   x = 629.62