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Finding the Fourth Proportional to 312, 430.20 and 285.90

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Solution

The fourth proportional to 312, 430.20 and 285.90 is: 394.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    312 : 430.20 = 285.90 : x
  2. Step 2: Convert to fraction form
    312/430.20 = 285.90/x
  3. Step 3: Cross multiply
    312x = 430.20 × 285.90
  4. Step 4: Simplify right side
    312x = 122,994.18
  5. Step 5: Solve for x
    x = 122,994.18/312
  6. Step 6: Final answer
    x = 394.21

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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.