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Finding the Fourth Proportional to 287.40, 396.60 and 156.40

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Solution

The fourth proportional to 287.40, 396.60 and 156.40 is: 215.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.40 : 396.60 = 156.40 : x
  2. Step 2: Convert to fraction form
    287.40/396.60 = 156.40/x
  3. Step 3: Cross multiply
    287.40x = 396.60 × 156.40
  4. Step 4: Simplify right side
    287.40x = 62,027.46
  5. Step 5: Solve for x
    x = 62,027.46/287.40
  6. Step 6: Final answer
    x = 215.83

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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.