Finding the Fourth Proportional to 9,991.51, 13,787.53 and 5,742.57

Step by Step Solution

1. Step 1: Write the proportion equation
   9,991.51 : 13,787.53 = 5,742.57 : x
2. Step 2: Convert to fraction form
   9,991.51/13,787.53 = 5,742.57/x
3. Step 3: Cross multiply
   9,991.51x = 13,787.53 × 5,742.57
4. Step 4: Simplify right side
   9,991.51x = 79,175,841.80
5. Step 5: Solve for x
   x = 79,175,841.80/9,991.51
6. Step 6: Final answer
   x = 7,924.31