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Finding the Fourth Proportional to 189.72, 284.48 and 90.78

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Solution

The fourth proportional to 189.72, 284.48 and 90.78 is: 136.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    189.72 : 284.48 = 90.78 : x
  2. Step 2: Convert to fraction form
    189.72/284.48 = 90.78/x
  3. Step 3: Cross multiply
    189.72x = 284.48 × 90.78
  4. Step 4: Simplify right side
    189.72x = 25,825.09
  5. Step 5: Solve for x
    x = 25,825.09/189.72
  6. Step 6: Final answer
    x = 136.12

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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.