Finding the Fourth Proportional to 1,401.90, 2,102.71 and 428.01

Step by Step Solution

1. Step 1: Write the proportion equation
   1,401.90 : 2,102.71 = 428.01 : x
2. Step 2: Convert to fraction form
   1,401.90/2,102.71 = 428.01/x
3. Step 3: Cross multiply
   1,401.90x = 2,102.71 × 428.01
4. Step 4: Simplify right side
   1,401.90x = 899,980.91
5. Step 5: Solve for x
   x = 899,980.91/1,401.90
6. Step 6: Final answer
   x = 641.97