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Finding the Fourth Proportional to 145, 216.41 and 128.56

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Solution

The fourth proportional to 145, 216.41 and 128.56 is: 191.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    145 : 216.41 = 128.56 : x
  2. Step 2: Convert to fraction form
    145/216.41 = 128.56/x
  3. Step 3: Cross multiply
    145x = 216.41 × 128.56
  4. Step 4: Simplify right side
    145x = 27,821.67
  5. Step 5: Solve for x
    x = 27,821.67/145
  6. Step 6: Final answer
    x = 191.87

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.