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Finding the Fourth Proportional to 318.50, 438.45 and 285.74

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Solution

The fourth proportional to 318.50, 438.45 and 285.74 is: 393.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.50 : 438.45 = 285.74 : x
  2. Step 2: Convert to fraction form
    318.50/438.45 = 285.74/x
  3. Step 3: Cross multiply
    318.50x = 438.45 × 285.74
  4. Step 4: Simplify right side
    318.50x = 125,282.70
  5. Step 5: Solve for x
    x = 125,282.70/318.50
  6. Step 6: Final answer
    x = 393.35

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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.