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Finding the Fourth Proportional to 420.42, 630.64 and 142.76

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Solution

The fourth proportional to 420.42, 630.64 and 142.76 is: 214.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.42 : 630.64 = 142.76 : x
  2. Step 2: Convert to fraction form
    420.42/630.64 = 142.76/x
  3. Step 3: Cross multiply
    420.42x = 630.64 × 142.76
  4. Step 4: Simplify right side
    420.42x = 90,031.12
  5. Step 5: Solve for x
    x = 90,031.12/420.42
  6. Step 6: Final answer
    x = 214.15

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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.