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Finding the Fourth Proportional to 151.78, 209.47 and 85.40

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Solution

The fourth proportional to 151.78, 209.47 and 85.40 is: 117.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    151.78 : 209.47 = 85.40 : x
  2. Step 2: Convert to fraction form
    151.78/209.47 = 85.40/x
  3. Step 3: Cross multiply
    151.78x = 209.47 × 85.40
  4. Step 4: Simplify right side
    151.78x = 17,887.59
  5. Step 5: Solve for x
    x = 17,887.59/151.78
  6. Step 6: Final answer
    x = 117.85

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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.