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Finding the Fourth Proportional to 278.40, 420 and 278.40

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Solution

The fourth proportional to 278.40, 420 and 278.40 is: 420

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.40 : 420 = 278.40 : x
  2. Step 2: Convert to fraction form
    278.40/420 = 278.40/x
  3. Step 3: Cross multiply
    278.40x = 420 × 278.40
  4. Step 4: Simplify right side
    278.40x = 116,928.00
  5. Step 5: Solve for x
    x = 116,928.00/278.40
  6. Step 6: Final answer
    x = 420

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.