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Finding the Fourth Proportional to 915, 1,371.25 and 421.12

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Solution

The fourth proportional to 915, 1,371.25 and 421.12 is: 631.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    915 : 1,371.25 = 421.12 : x
  2. Step 2: Convert to fraction form
    915/1,371.25 = 421.12/x
  3. Step 3: Cross multiply
    915x = 1,371.25 × 421.12
  4. Step 4: Simplify right side
    915x = 577,460.80
  5. Step 5: Solve for x
    x = 577,460.80/915
  6. Step 6: Final answer
    x = 631.10

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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.