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Finding the Fourth Proportional to 645.60, 968.40 and 386.40

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Solution

The fourth proportional to 645.60, 968.40 and 386.40 is: 579.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.60 : 968.40 = 386.40 : x
  2. Step 2: Convert to fraction form
    645.60/968.40 = 386.40/x
  3. Step 3: Cross multiply
    645.60x = 968.40 × 386.40
  4. Step 4: Simplify right side
    645.60x = 374,189.76
  5. Step 5: Solve for x
    x = 374,189.76/645.60
  6. Step 6: Final answer
    x = 579.60

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.