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Finding the Fourth Proportional to 215.40, 323.05 and 99.72

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Solution

The fourth proportional to 215.40, 323.05 and 99.72 is: 149.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.40 : 323.05 = 99.72 : x
  2. Step 2: Convert to fraction form
    215.40/323.05 = 99.72/x
  3. Step 3: Cross multiply
    215.40x = 323.05 × 99.72
  4. Step 4: Simplify right side
    215.40x = 32,214.55
  5. Step 5: Solve for x
    x = 32,214.55/215.40
  6. Step 6: Final answer
    x = 149.56

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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.