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Finding the Fourth Proportional to 189.86, 284.72 and 87.20

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Solution

The fourth proportional to 189.86, 284.72 and 87.20 is: 130.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    189.86 : 284.72 = 87.20 : x
  2. Step 2: Convert to fraction form
    189.86/284.72 = 87.20/x
  3. Step 3: Cross multiply
    189.86x = 284.72 × 87.20
  4. Step 4: Simplify right side
    189.86x = 24,825.72
  5. Step 5: Solve for x
    x = 24,825.72/189.86
  6. Step 6: Final answer
    x = 130.76

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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.