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Finding the Fourth Proportional to 261.29, 391.85 and 90.25

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Solution

The fourth proportional to 261.29, 391.85 and 90.25 is: 135.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.29 : 391.85 = 90.25 : x
  2. Step 2: Convert to fraction form
    261.29/391.85 = 90.25/x
  3. Step 3: Cross multiply
    261.29x = 391.85 × 90.25
  4. Step 4: Simplify right side
    261.29x = 35,364.46
  5. Step 5: Solve for x
    x = 35,364.46/261.29
  6. Step 6: Final answer
    x = 135.35

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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.