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Finding the Fourth Proportional to 156.39, 215.79 and 87.39

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Solution

The fourth proportional to 156.39, 215.79 and 87.39 is: 120.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.39 : 215.79 = 87.39 : x
  2. Step 2: Convert to fraction form
    156.39/215.79 = 87.39/x
  3. Step 3: Cross multiply
    156.39x = 215.79 × 87.39
  4. Step 4: Simplify right side
    156.39x = 18,857.89
  5. Step 5: Solve for x
    x = 18,857.89/156.39
  6. Step 6: Final answer
    x = 120.58

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.