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Finding the Fourth Proportional to 78, 117.05 and 72.87

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Solution

The fourth proportional to 78, 117.05 and 72.87 is: 109.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    78 : 117.05 = 72.87 : x
  2. Step 2: Convert to fraction form
    78/117.05 = 72.87/x
  3. Step 3: Cross multiply
    78x = 117.05 × 72.87
  4. Step 4: Simplify right side
    78x = 8,529.07
  5. Step 5: Solve for x
    x = 8,529.07/78
  6. Step 6: Final answer
    x = 109.35

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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.