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Finding the Fourth Proportional to 420.86, 631.08 and 315.78

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Solution

The fourth proportional to 420.86, 631.08 and 315.78 is: 473.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.86 : 631.08 = 315.78 : x
  2. Step 2: Convert to fraction form
    420.86/631.08 = 315.78/x
  3. Step 3: Cross multiply
    420.86x = 631.08 × 315.78
  4. Step 4: Simplify right side
    420.86x = 199,281.26
  5. Step 5: Solve for x
    x = 199,281.26/420.86
  6. Step 6: Final answer
    x = 473.51

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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.