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Finding the Fourth Proportional to 145.86, 218.88 and 81.78

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Solution

The fourth proportional to 145.86, 218.88 and 81.78 is: 122.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    145.86 : 218.88 = 81.78 : x
  2. Step 2: Convert to fraction form
    145.86/218.88 = 81.78/x
  3. Step 3: Cross multiply
    145.86x = 218.88 × 81.78
  4. Step 4: Simplify right side
    145.86x = 17,900.01
  5. Step 5: Solve for x
    x = 17,900.01/145.86
  6. Step 6: Final answer
    x = 122.72

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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.