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Finding the Fourth Proportional to 319.11, 478.40 and 261.20

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Solution

The fourth proportional to 319.11, 478.40 and 261.20 is: 391.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    319.11 : 478.40 = 261.20 : x
  2. Step 2: Convert to fraction form
    319.11/478.40 = 261.20/x
  3. Step 3: Cross multiply
    319.11x = 478.40 × 261.20
  4. Step 4: Simplify right side
    319.11x = 124,954.38
  5. Step 5: Solve for x
    x = 124,954.38/319.11
  6. Step 6: Final answer
    x = 391.57

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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.