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Finding the Fourth Proportional to 135.72, 203.70 and 78

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Solution

The fourth proportional to 135.72, 203.70 and 78 is: 117.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    135.72 : 203.70 = 78 : x
  2. Step 2: Convert to fraction form
    135.72/203.70 = 78/x
  3. Step 3: Cross multiply
    135.72x = 203.70 × 78
  4. Step 4: Simplify right side
    135.72x = 15,888.60
  5. Step 5: Solve for x
    x = 15,888.60/135.72
  6. Step 6: Final answer
    x = 117.07

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.