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Finding the Fourth Proportional to 405.78, 560.15 and 312.49

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Solution

The fourth proportional to 405.78, 560.15 and 312.49 is: 431.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.78 : 560.15 = 312.49 : x
  2. Step 2: Convert to fraction form
    405.78/560.15 = 312.49/x
  3. Step 3: Cross multiply
    405.78x = 560.15 × 312.49
  4. Step 4: Simplify right side
    405.78x = 175,040.65
  5. Step 5: Solve for x
    x = 175,040.65/405.78
  6. Step 6: Final answer
    x = 431.37

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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.