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Finding the Fourth Proportional to 261.25, 391.88 and 90.25

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Solution

The fourth proportional to 261.25, 391.88 and 90.25 is: 135.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.25 : 391.88 = 90.25 : x
  2. Step 2: Convert to fraction form
    261.25/391.88 = 90.25/x
  3. Step 3: Cross multiply
    261.25x = 391.88 × 90.25
  4. Step 4: Simplify right side
    261.25x = 35,367.17
  5. Step 5: Solve for x
    x = 35,367.17/261.25
  6. Step 6: Final answer
    x = 135.38

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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.