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Finding the Fourth Proportional to 390.42, 586.08 and 318.78

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Solution

The fourth proportional to 390.42, 586.08 and 318.78 is: 478.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.42 : 586.08 = 318.78 : x
  2. Step 2: Convert to fraction form
    390.42/586.08 = 318.78/x
  3. Step 3: Cross multiply
    390.42x = 586.08 × 318.78
  4. Step 4: Simplify right side
    390.42x = 186,830.58
  5. Step 5: Solve for x
    x = 186,830.58/390.42
  6. Step 6: Final answer
    x = 478.54

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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.