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Finding the Fourth Proportional to 78.72, 117.26 and 74.40

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Solution

The fourth proportional to 78.72, 117.26 and 74.40 is: 110.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.72 : 117.26 = 74.40 : x
  2. Step 2: Convert to fraction form
    78.72/117.26 = 74.40/x
  3. Step 3: Cross multiply
    78.72x = 117.26 × 74.40
  4. Step 4: Simplify right side
    78.72x = 8,723.77
  5. Step 5: Solve for x
    x = 8,723.77/78.72
  6. Step 6: Final answer
    x = 110.82

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.