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Finding the Fourth Proportional to 420.85, 631.42 and 215.51

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Solution

The fourth proportional to 420.85, 631.42 and 215.51 is: 323.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.85 : 631.42 = 215.51 : x
  2. Step 2: Convert to fraction form
    420.85/631.42 = 215.51/x
  3. Step 3: Cross multiply
    420.85x = 631.42 × 215.51
  4. Step 4: Simplify right side
    420.85x = 136,077.79
  5. Step 5: Solve for x
    x = 136,077.79/420.85
  6. Step 6: Final answer
    x = 323.34

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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.