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Finding the Fourth Proportional to 644.40, 889.57 and 621.31

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Solution

The fourth proportional to 644.40, 889.57 and 621.31 is: 857.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    644.40 : 889.57 = 621.31 : x
  2. Step 2: Convert to fraction form
    644.40/889.57 = 621.31/x
  3. Step 3: Cross multiply
    644.40x = 889.57 × 621.31
  4. Step 4: Simplify right side
    644.40x = 552,698.74
  5. Step 5: Solve for x
    x = 552,698.74/644.40
  6. Step 6: Final answer
    x = 857.70

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.