Finding the Fourth Proportional to 1,638.60, 2,459.10 and 1,276.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,638.60 : 2,459.10 = 1,276.50 : x
2. Step 2: Convert to fraction form
   1,638.60/2,459.10 = 1,276.50/x
3. Step 3: Cross multiply
   1,638.60x = 2,459.10 × 1,276.50
4. Step 4: Simplify right side
   1,638.60x = 3,139,041.15
5. Step 5: Solve for x
   x = 3,139,041.15/1,638.60
6. Step 6: Final answer
   x = 1,915.68