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Finding the Fourth Proportional to 129, 178 and 85.39

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Solution

The fourth proportional to 129, 178 and 85.39 is: 117.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    129 : 178 = 85.39 : x
  2. Step 2: Convert to fraction form
    129/178 = 85.39/x
  3. Step 3: Cross multiply
    129x = 178 × 85.39
  4. Step 4: Simplify right side
    129x = 15,199.42
  5. Step 5: Solve for x
    x = 15,199.42/129
  6. Step 6: Final answer
    x = 117.82

Related Problems

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Half scale
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Double scale
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Similar ratio
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1.5x scale

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.