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Finding the Fourth Proportional to 78.39, 117.45 and 54.36

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Solution

The fourth proportional to 78.39, 117.45 and 54.36 is: 81.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.39 : 117.45 = 54.36 : x
  2. Step 2: Convert to fraction form
    78.39/117.45 = 54.36/x
  3. Step 3: Cross multiply
    78.39x = 117.45 × 54.36
  4. Step 4: Simplify right side
    78.39x = 6,384.58
  5. Step 5: Solve for x
    x = 6,384.58/78.39
  6. Step 6: Final answer
    x = 81.45

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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.