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Finding the Fourth Proportional to 388.20, 535.88 and 257.40

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Solution

The fourth proportional to 388.20, 535.88 and 257.40 is: 355.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    388.20 : 535.88 = 257.40 : x
  2. Step 2: Convert to fraction form
    388.20/535.88 = 257.40/x
  3. Step 3: Cross multiply
    388.20x = 535.88 × 257.40
  4. Step 4: Simplify right side
    388.20x = 137,935.51
  5. Step 5: Solve for x
    x = 137,935.51/388.20
  6. Step 6: Final answer
    x = 355.32

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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.