Finding the Fourth Proportional to 1,388.16, 1,915.38 and 790.52

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.16 : 1,915.38 = 790.52 : x
2. Step 2: Convert to fraction form
   1,388.16/1,915.38 = 790.52/x
3. Step 3: Cross multiply
   1,388.16x = 1,915.38 × 790.52
4. Step 4: Simplify right side
   1,388.16x = 1,514,136.62
5. Step 5: Solve for x
   x = 1,514,136.62/1,388.16
6. Step 6: Final answer
   x = 1,090.75