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Finding the Fourth Proportional to 109.78, 151.56 and 85.18

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Solution

The fourth proportional to 109.78, 151.56 and 85.18 is: 117.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.78 : 151.56 = 85.18 : x
  2. Step 2: Convert to fraction form
    109.78/151.56 = 85.18/x
  3. Step 3: Cross multiply
    109.78x = 151.56 × 85.18
  4. Step 4: Simplify right side
    109.78x = 12,909.88
  5. Step 5: Solve for x
    x = 12,909.88/109.78
  6. Step 6: Final answer
    x = 117.60

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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.