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Finding the Fourth Proportional to 216.51, 298.80 and 129.20

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Solution

The fourth proportional to 216.51, 298.80 and 129.20 is: 178.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    216.51 : 298.80 = 129.20 : x
  2. Step 2: Convert to fraction form
    216.51/298.80 = 129.20/x
  3. Step 3: Cross multiply
    216.51x = 298.80 × 129.20
  4. Step 4: Simplify right side
    216.51x = 38,603.47
  5. Step 5: Solve for x
    x = 38,603.47/216.51
  6. Step 6: Final answer
    x = 178.30

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.