Finding the Fourth Proportional to 1,312.86, 1,968.69 and 388.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,312.86 : 1,968.69 = 388.10 : x
2. Step 2: Convert to fraction form
   1,312.86/1,968.69 = 388.10/x
3. Step 3: Cross multiply
   1,312.86x = 1,968.69 × 388.10
4. Step 4: Simplify right side
   1,312.86x = 764,040.20
5. Step 5: Solve for x
   x = 764,040.20/1,312.86
6. Step 6: Final answer
   x = 581.97