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Finding the Fourth Proportional to 78.90, 118.49 and 54.87

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Solution

The fourth proportional to 78.90, 118.49 and 54.87 is: 82.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.90 : 118.49 = 54.87 : x
  2. Step 2: Convert to fraction form
    78.90/118.49 = 54.87/x
  3. Step 3: Cross multiply
    78.90x = 118.49 × 54.87
  4. Step 4: Simplify right side
    78.90x = 6,501.55
  5. Step 5: Solve for x
    x = 6,501.55/78.90
  6. Step 6: Final answer
    x = 82.40

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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.