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Finding the Fourth Proportional to 666.40, 999.60 and 420.36

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Solution

The fourth proportional to 666.40, 999.60 and 420.36 is: 630.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.40 : 999.60 = 420.36 : x
  2. Step 2: Convert to fraction form
    666.40/999.60 = 420.36/x
  3. Step 3: Cross multiply
    666.40x = 999.60 × 420.36
  4. Step 4: Simplify right side
    666.40x = 420,191.86
  5. Step 5: Solve for x
    x = 420,191.86/666.40
  6. Step 6: Final answer
    x = 630.54

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Double scale
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Similar ratio
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1.5x scale

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.