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Finding the Fourth Proportional to 285.40, 392.70 and 278.92

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Solution

The fourth proportional to 285.40, 392.70 and 278.92 is: 383.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    285.40 : 392.70 = 278.92 : x
  2. Step 2: Convert to fraction form
    285.40/392.70 = 278.92/x
  3. Step 3: Cross multiply
    285.40x = 392.70 × 278.92
  4. Step 4: Simplify right side
    285.40x = 109,531.88
  5. Step 5: Solve for x
    x = 109,531.88/285.40
  6. Step 6: Final answer
    x = 383.78

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.