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Finding the Fourth Proportional to 390.76, 585.40 and 147.12

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Solution

The fourth proportional to 390.76, 585.40 and 147.12 is: 220.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.76 : 585.40 = 147.12 : x
  2. Step 2: Convert to fraction form
    390.76/585.40 = 147.12/x
  3. Step 3: Cross multiply
    390.76x = 585.40 × 147.12
  4. Step 4: Simplify right side
    390.76x = 86,124.05
  5. Step 5: Solve for x
    x = 86,124.05/390.76
  6. Step 6: Final answer
    x = 220.40

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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.