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Finding the Fourth Proportional to 645.76, 890.61 and 485.53

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Solution

The fourth proportional to 645.76, 890.61 and 485.53 is: 669.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.76 : 890.61 = 485.53 : x
  2. Step 2: Convert to fraction form
    645.76/890.61 = 485.53/x
  3. Step 3: Cross multiply
    645.76x = 890.61 × 485.53
  4. Step 4: Simplify right side
    645.76x = 432,417.87
  5. Step 5: Solve for x
    x = 432,417.87/645.76
  6. Step 6: Final answer
    x = 669.63

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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.