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Finding the Fourth Proportional to 156.60, 215.64 and 128.88

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Solution

The fourth proportional to 156.60, 215.64 and 128.88 is: 177.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    156.60 : 215.64 = 128.88 : x
  2. Step 2: Convert to fraction form
    156.60/215.64 = 128.88/x
  3. Step 3: Cross multiply
    156.60x = 215.64 × 128.88
  4. Step 4: Simplify right side
    156.60x = 27,791.68
  5. Step 5: Solve for x
    x = 27,791.68/156.60
  6. Step 6: Final answer
    x = 177.47

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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.