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Finding the Fourth Proportional to 128.61, 177.46 and 79.47

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Solution

The fourth proportional to 128.61, 177.46 and 79.47 is: 109.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.61 : 177.46 = 79.47 : x
  2. Step 2: Convert to fraction form
    128.61/177.46 = 79.47/x
  3. Step 3: Cross multiply
    128.61x = 177.46 × 79.47
  4. Step 4: Simplify right side
    128.61x = 14,102.75
  5. Step 5: Solve for x
    x = 14,102.75/128.61
  6. Step 6: Final answer
    x = 109.66

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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.