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Finding the Fourth Proportional to 287.40, 431.13 and 257.16

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Solution

The fourth proportional to 287.40, 431.13 and 257.16 is: 385.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.40 : 431.13 = 257.16 : x
  2. Step 2: Convert to fraction form
    287.40/431.13 = 257.16/x
  3. Step 3: Cross multiply
    287.40x = 431.13 × 257.16
  4. Step 4: Simplify right side
    287.40x = 110,869.39
  5. Step 5: Solve for x
    x = 110,869.39/287.40
  6. Step 6: Final answer
    x = 385.77

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.