Finding the Fourth Proportional to 1,987.54, 2,742.30 and 1,288.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,987.54 : 2,742.30 = 1,288.50 : x
2. Step 2: Convert to fraction form
   1,987.54/2,742.30 = 1,288.50/x
3. Step 3: Cross multiply
   1,987.54x = 2,742.30 × 1,288.50
4. Step 4: Simplify right side
   1,987.54x = 3,533,453.55
5. Step 5: Solve for x
   x = 3,533,453.55/1,987.54
6. Step 6: Final answer
   x = 1,777.80