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Finding the Fourth Proportional to 151.21, 208.65 and 85.72

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Solution

The fourth proportional to 151.21, 208.65 and 85.72 is: 118.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    151.21 : 208.65 = 85.72 : x
  2. Step 2: Convert to fraction form
    151.21/208.65 = 85.72/x
  3. Step 3: Cross multiply
    151.21x = 208.65 × 85.72
  4. Step 4: Simplify right side
    151.21x = 17,885.48
  5. Step 5: Solve for x
    x = 17,885.48/151.21
  6. Step 6: Final answer
    x = 118.28

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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.