Finding the Fourth Proportional to 56,128.68, 77,457.42 and 30,978

Step by Step Solution

1. Step 1: Write the proportion equation
   56,128.68 : 77,457.42 = 30,978 : x
2. Step 2: Convert to fraction form
   56,128.68/77,457.42 = 30,978/x
3. Step 3: Cross multiply
   56,128.68x = 77,457.42 × 30,978
4. Step 4: Simplify right side
   56,128.68x = 2,399,475,956.76
5. Step 5: Solve for x
   x = 2,399,475,956.76/56,128.68
6. Step 6: Final answer
   x = 42,749.55