Finding the Fourth Proportional to 2,547.78, 3,820.69 and 987.72

Step by Step Solution

1. Step 1: Write the proportion equation
   2,547.78 : 3,820.69 = 987.72 : x
2. Step 2: Convert to fraction form
   2,547.78/3,820.69 = 987.72/x
3. Step 3: Cross multiply
   2,547.78x = 3,820.69 × 987.72
4. Step 4: Simplify right side
   2,547.78x = 3,773,771.93
5. Step 5: Solve for x
   x = 3,773,771.93/2,547.78
6. Step 6: Final answer
   x = 1,481.20