Finding the Fourth Proportional to 1,404.72, 1,937.52 and 990

Step by Step Solution

1. Step 1: Write the proportion equation
   1,404.72 : 1,937.52 = 990 : x
2. Step 2: Convert to fraction form
   1,404.72/1,937.52 = 990/x
3. Step 3: Cross multiply
   1,404.72x = 1,937.52 × 990
4. Step 4: Simplify right side
   1,404.72x = 1,918,144.80
5. Step 5: Solve for x
   x = 1,918,144.80/1,404.72
6. Step 6: Final answer
   x = 1,365.50