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Finding the Fourth Proportional to 76.80, 114.72 and 74.64

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Solution

The fourth proportional to 76.80, 114.72 and 74.64 is: 111.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.80 : 114.72 = 74.64 : x
  2. Step 2: Convert to fraction form
    76.80/114.72 = 74.64/x
  3. Step 3: Cross multiply
    76.80x = 114.72 × 74.64
  4. Step 4: Simplify right side
    76.80x = 8,562.70
  5. Step 5: Solve for x
    x = 8,562.70/76.80
  6. Step 6: Final answer
    x = 111.49

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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.