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Finding the Fourth Proportional to 78.60, 118.40 and 67.80

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Solution

The fourth proportional to 78.60, 118.40 and 67.80 is: 102.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.60 : 118.40 = 67.80 : x
  2. Step 2: Convert to fraction form
    78.60/118.40 = 67.80/x
  3. Step 3: Cross multiply
    78.60x = 118.40 × 67.80
  4. Step 4: Simplify right side
    78.60x = 8,027.52
  5. Step 5: Solve for x
    x = 8,027.52/78.60
  6. Step 6: Final answer
    x = 102.13

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.