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Finding the Fourth Proportional to 156.79, 215.65 and 128.58

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Solution

The fourth proportional to 156.79, 215.65 and 128.58 is: 176.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.79 : 215.65 = 128.58 : x
  2. Step 2: Convert to fraction form
    156.79/215.65 = 128.58/x
  3. Step 3: Cross multiply
    156.79x = 215.65 × 128.58
  4. Step 4: Simplify right side
    156.79x = 27,726.91
  5. Step 5: Solve for x
    x = 27,726.91/156.79
  6. Step 6: Final answer
    x = 176.85

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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.