Finding the Fourth Proportional to 9,991.38, 13,788.72 and 5,743.80

Step by Step Solution

1. Step 1: Write the proportion equation
   9,991.38 : 13,788.72 = 5,743.80 : x
2. Step 2: Convert to fraction form
   9,991.38/13,788.72 = 5,743.80/x
3. Step 3: Cross multiply
   9,991.38x = 13,788.72 × 5,743.80
4. Step 4: Simplify right side
   9,991.38x = 79,199,649.94
5. Step 5: Solve for x
   x = 79,199,649.94/9,991.38
6. Step 6: Final answer
   x = 7,926.80