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Finding the Fourth Proportional to 145.65, 218.28 and 81.39

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Solution

The fourth proportional to 145.65, 218.28 and 81.39 is: 121.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    145.65 : 218.28 = 81.39 : x
  2. Step 2: Convert to fraction form
    145.65/218.28 = 81.39/x
  3. Step 3: Cross multiply
    145.65x = 218.28 × 81.39
  4. Step 4: Simplify right side
    145.65x = 17,765.81
  5. Step 5: Solve for x
    x = 17,765.81/145.65
  6. Step 6: Final answer
    x = 121.98

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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.