Finding the Fourth Proportional to 13,325.42, 19,981.38 and 7,780.16

Step by Step Solution

1. Step 1: Write the proportion equation
   13,325.42 : 19,981.38 = 7,780.16 : x
2. Step 2: Convert to fraction form
   13,325.42/19,981.38 = 7,780.16/x
3. Step 3: Cross multiply
   13,325.42x = 19,981.38 × 7,780.16
4. Step 4: Simplify right side
   13,325.42x = 155,458,333.42
5. Step 5: Solve for x
   x = 155,458,333.42/13,325.42
6. Step 6: Final answer
   x = 11,666.30