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Finding the Fourth Proportional to 76.40, 114.58 and 61.28

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Solution

The fourth proportional to 76.40, 114.58 and 61.28 is: 91.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.40 : 114.58 = 61.28 : x
  2. Step 2: Convert to fraction form
    76.40/114.58 = 61.28/x
  3. Step 3: Cross multiply
    76.40x = 114.58 × 61.28
  4. Step 4: Simplify right side
    76.40x = 7,021.46
  5. Step 5: Solve for x
    x = 7,021.46/76.40
  6. Step 6: Final answer
    x = 91.90

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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.