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Finding the Fourth Proportional to 656.40, 905.81 and 420.02

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Solution

The fourth proportional to 656.40, 905.81 and 420.02 is: 579.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    656.40 : 905.81 = 420.02 : x
  2. Step 2: Convert to fraction form
    656.40/905.81 = 420.02/x
  3. Step 3: Cross multiply
    656.40x = 905.81 × 420.02
  4. Step 4: Simplify right side
    656.40x = 380,451.69
  5. Step 5: Solve for x
    x = 380,451.69/656.40
  6. Step 6: Final answer
    x = 579.60

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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.