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Finding the Fourth Proportional to 645.40, 890.76 and 479.80

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Solution

The fourth proportional to 645.40, 890.76 and 479.80 is: 662.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.40 : 890.76 = 479.80 : x
  2. Step 2: Convert to fraction form
    645.40/890.76 = 479.80/x
  3. Step 3: Cross multiply
    645.40x = 890.76 × 479.80
  4. Step 4: Simplify right side
    645.40x = 427,386.65
  5. Step 5: Solve for x
    x = 427,386.65/645.40
  6. Step 6: Final answer
    x = 662.20

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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.