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Finding the Fourth Proportional to 280.78, 387.47 and 156.45

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Solution

The fourth proportional to 280.78, 387.47 and 156.45 is: 215.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.78 : 387.47 = 156.45 : x
  2. Step 2: Convert to fraction form
    280.78/387.47 = 156.45/x
  3. Step 3: Cross multiply
    280.78x = 387.47 × 156.45
  4. Step 4: Simplify right side
    280.78x = 60,617.93
  5. Step 5: Solve for x
    x = 60,617.93/280.78
  6. Step 6: Final answer
    x = 215.89

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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.