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Finding the Fourth Proportional to 611.06, 915.87 and 391.40

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Solution

The fourth proportional to 611.06, 915.87 and 391.40 is: 586.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    611.06 : 915.87 = 391.40 : x
  2. Step 2: Convert to fraction form
    611.06/915.87 = 391.40/x
  3. Step 3: Cross multiply
    611.06x = 915.87 × 391.40
  4. Step 4: Simplify right side
    611.06x = 358,471.52
  5. Step 5: Solve for x
    x = 358,471.52/611.06
  6. Step 6: Final answer
    x = 586.64

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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.