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Finding the Fourth Proportional to 318.70, 478.20 and 145.42

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Solution

The fourth proportional to 318.70, 478.20 and 145.42 is: 218.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    318.70 : 478.20 = 145.42 : x
  2. Step 2: Convert to fraction form
    318.70/478.20 = 145.42/x
  3. Step 3: Cross multiply
    318.70x = 478.20 × 145.42
  4. Step 4: Simplify right side
    318.70x = 69,539.84
  5. Step 5: Solve for x
    x = 69,539.84/318.70
  6. Step 6: Final answer
    x = 218.20

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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.