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Finding the Fourth Proportional to 261.51, 391.98 and 90.39

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Solution

The fourth proportional to 261.51, 391.98 and 90.39 is: 135.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.51 : 391.98 = 90.39 : x
  2. Step 2: Convert to fraction form
    261.51/391.98 = 90.39/x
  3. Step 3: Cross multiply
    261.51x = 391.98 × 90.39
  4. Step 4: Simplify right side
    261.51x = 35,431.07
  5. Step 5: Solve for x
    x = 35,431.07/261.51
  6. Step 6: Final answer
    x = 135.49

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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.