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Finding the Fourth Proportional to 420.72, 630.38 and 290.78

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Solution

The fourth proportional to 420.72, 630.38 and 290.78 is: 435.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.72 : 630.38 = 290.78 : x
  2. Step 2: Convert to fraction form
    420.72/630.38 = 290.78/x
  3. Step 3: Cross multiply
    420.72x = 630.38 × 290.78
  4. Step 4: Simplify right side
    420.72x = 183,301.90
  5. Step 5: Solve for x
    x = 183,301.90/420.72
  6. Step 6: Final answer
    x = 435.69

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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.