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Finding the Fourth Proportional to 78.48, 108.12 and 74.64

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Solution

The fourth proportional to 78.48, 108.12 and 74.64 is: 102.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.48 : 108.12 = 74.64 : x
  2. Step 2: Convert to fraction form
    78.48/108.12 = 74.64/x
  3. Step 3: Cross multiply
    78.48x = 108.12 × 74.64
  4. Step 4: Simplify right side
    78.48x = 8,070.08
  5. Step 5: Solve for x
    x = 8,070.08/78.48
  6. Step 6: Final answer
    x = 102.83

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.