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Finding the Fourth Proportional to 215.14, 322.79 and 78.20

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Solution

The fourth proportional to 215.14, 322.79 and 78.20 is: 117.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.14 : 322.79 = 78.20 : x
  2. Step 2: Convert to fraction form
    215.14/322.79 = 78.20/x
  3. Step 3: Cross multiply
    215.14x = 322.79 × 78.20
  4. Step 4: Simplify right side
    215.14x = 25,241.08
  5. Step 5: Solve for x
    x = 25,241.08/215.14
  6. Step 6: Final answer
    x = 117.32

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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.