Finding the Fourth Proportional to 1,428.76, 1,971.60 and 1,386.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,428.76 : 1,971.60 = 1,386.82 : x
2. Step 2: Convert to fraction form
   1,428.76/1,971.60 = 1,386.82/x
3. Step 3: Cross multiply
   1,428.76x = 1,971.60 × 1,386.82
4. Step 4: Simplify right side
   1,428.76x = 2,734,254.31
5. Step 5: Solve for x
   x = 2,734,254.31/1,428.76
6. Step 6: Final answer
   x = 1,913.73