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Finding the Fourth Proportional to 391.40, 586.70 and 217.80

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Solution

The fourth proportional to 391.40, 586.70 and 217.80 is: 326.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    391.40 : 586.70 = 217.80 : x
  2. Step 2: Convert to fraction form
    391.40/586.70 = 217.80/x
  3. Step 3: Cross multiply
    391.40x = 586.70 × 217.80
  4. Step 4: Simplify right side
    391.40x = 127,783.26
  5. Step 5: Solve for x
    x = 127,783.26/391.40
  6. Step 6: Final answer
    x = 326.48

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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.